Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: V8Demon on December 03, 2013, 06:02:37 PM

Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 03, 2013, 06:02:37 PM
Hey kiddies!

It's been awhile.  Not much to report on my end.  Looking for someone to repaint a few panels on the Cougar that the last guy screwed up and refuses to make good on (deadbeat).  Wish I had the patience and facilities to do body work myself.....

I digress.

Got one for you that honestly has me stumped...
This is a buddies car that he recently acquired.  It's an '87 Mustang Gt with t Tops and a 5-speed, still running speed density with a DA1 ECU.  The car has stock everything save for exhaust and gears and sat for about 3 years before he got it.  Needless to say it needed a little TLC to get it going.

As it sits right now it runs horrendously rich at all times.  The car also is quite hard to start after warm.  Cold startup is flawless.  On warm/hot starup she turns over as if it has a severely low battery that sat in an Alaskan winter overnight. 

Battery is new, distributor and TFI module are known good.  Fuel pressure regulator is stock.  Fuel pressure is good and within parameters.  When the problem was first described to me I thought about the HEGO harness and the possibility of it not being hooked up correctly.  My buddy chased the wires last night and it is in fact hooked up correctly.  Interestingly enough, disconnecting the HEGO harness from the engine harness shows no change in how it runs.  Due to the richness, the car does not want to idle lower then 850 RPM and even at that RPM it's quite choppy.  It smooths out if it is bumped to 1000. 

I should add that the o2 sensors are new as well.  Battery voltage is good and alternator is charging like a champ.  There are no extra electrical components added to the car.  Still has the stock speakers and head unit.

I'm thinking it's either a wiring problem somewhere in the HEGO harness or a faulty ECU.  Am I on the right track here?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: jandmmustangs on December 03, 2013, 06:20:46 PM
Your thoughts are possible. I'd check the fpr for leaks. Pull the vac hose off of it and see if your smell fuel.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: STANG8U on December 03, 2013, 06:41:15 PM
87 t top kinda rare

Pull any codes ?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 03, 2013, 06:44:02 PM
I'd look for corrosion in/on the ground wires. They can loose conductivity over time. Replace the battery ground wire and check the EEC ground. I've cleaned the connection before (thinking that was enough)  and actually had a bad cable. Once I split it open it was filled with corrosion. That corrosion caused a resistance and led to problems.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 03, 2013, 06:48:58 PM
One other thing to check would be the computer's temp sensor. (Not the one for the gauge.) The computer might be thinking the car is cold all the time and adding fuel, not getting out of warm-up logic. That might explain why the O2 sensor made no difference.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: STANG8U on December 03, 2013, 07:18:07 PM
That could be it
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 03, 2013, 07:48:10 PM
FPR is good.  No smells.  It's getting a good vacuum signal.  All grounds have been replaced.  The guy who picked this car up has been pretty thorough due to how long it sat.  No codes other than canister purge solenoid which is out of the car (it was bad).  I've seen these cars run without those before without issue.

Quote from: flylear45;425207
One other thing to check would be the computer's temp sensor. (Not the one for the gauge.) The computer might be thinking the car is cold all the time and adding fuel, not getting out of warm-up logic. That might explain why the O2 sensor made no difference.

I'll let him know on that.  Didn't even come to mind to me when I was giving the car a once over. 

I'll keep you guys posted ;)
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Dougy_Fresh on December 03, 2013, 10:12:37 PM
i'd start with checking all the sensors, mainly the coolant temp sensor, intake air temp sensor, and map sensor
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 03, 2013, 10:20:17 PM
It is a possibility even without a code. The computer throws a code when a sensor is out of range. If it fails to read properly but is in range.....no code. I just fixed an issue similar to this on my son's 89 Daytona. Modern cars are a bit smarter, but they still lie, too.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: 88turbo on December 04, 2013, 04:42:36 AM
Paul, Check the TPS for broken wires.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Beau on December 04, 2013, 04:57:15 AM
X2 on TPS or wiring. I had a coolant temp sensor go "bad" and cause symptoms like you describe, as well. That was on a 5.0 F series truck. Later on, the FPR went bad, and it also caused the same problem. Would run like a raped ape till the engine got warm, then acted like it was getting loads of fuel dumped in (because it was, technically).

If all that pans out, I'd also check the O2's and their connections/wiring.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: beast50 on December 04, 2013, 05:34:36 AM
Clogged cat?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Haystack on December 04, 2013, 06:02:43 AM
check the timing. maybe someone swapped a cam in and set it too far advanced or retarded, or dropped the dist in wrong. could be firing all the injectors to the wrong cylinders.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 04, 2013, 06:40:06 AM
Quote from: 88turbo;425221
Paul, Check the TPS for broken wires.



That WOULD throw a code.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 04, 2013, 07:06:35 AM
Quote from: Dougy_Fresh;425213
i'd start with checking all the sensors, mainly the coolant temp sensor, intake air temp sensor, and map sensor


Yes, and the vacuum hoses, too. The map line is known to crack.

He did cap off the line to the manifold when he removed the charcoal cannister?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 04, 2013, 01:58:21 PM
Quote from: 88turbo;425221
Paul, Check the TPS for broken wires.

TPS is good.  No flat spots .8v or so at KOEO on the idle screw stop and sweeps to 4.5v in the WOT position.

Quote
It is a possibility even without a code. The computer throws a code when a sensor is out of range. If it fails to read properly but is in range.....no code. I just fixed an issue similar to this on my son's 89 Daytona. Modern cars are a bit smarter, but they still lie, too.

There's an old thread in here in where I basically confirm that with the HEGO system.  I had a custom exhaust fabricated and long story short My o2 sensor harness had been swapped to read the wrong banks.  No codes whatsoever.....  Found it:  http://www.foxtbirdcougarforums.com/showthread.php?21560-White-10-pin-connector

Quote
check the timing. maybe someone swapped a cam in and set it too far advanced or retarded, or dropped the dist in wrong. could be firing all the injectors to the wrong cylinders.

Timing's @ 12, spout's connected, stock cam, distributor is installed correctly.  Checked all this previously.

Quote
He did cap off the line to the manifold when he removed the charcoal cannister?

ZERO VACUUM LEAKS. 

This is yet another reason why I prefer finding a T-Bird or Cougar over a Mustang.  They're usually stock or near it and those who DO modify them are a smaller community -- hell, most everyone I've ever met with a modified Cat or Bird is aware of this site! 

If I ever purchase a fox Mustang myself, you can bet your ass I'll shop around for one who's owner had a clue and not some kid who hacks things to pieces.....  I see them go for top dollar hacked up and running like garbage....
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flylear45 on December 04, 2013, 04:13:57 PM
Sounds like you guys are on it pretty well. At this point I'm guessing it's either a weird sensor IAT, CLT, or MAP, or the EEC computer is Tango Uniform. You are SURE the computer ground is good. (I'm sure you checked it.)
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: thunderjet302 on December 04, 2013, 04:15:44 PM
Quote from: Dougy_Fresh;425213
i'd start with checking all the sensors, mainly the coolant temp sensor, intake air temp sensor, and map sensor


I'd check the coolant temp sensor. It acts like a choke to enrich the mixture on a cold start. If it's acting up the engine will run rich all the time. You said that on a cold start it runs fine. That points in the direction of the coolant temp sensor.


Quote from: V8Demon;425231
TPS is good.  This is yet another reason why I prefer finding a T-Bird or Cougar over a Mustang.  They're usually stock or near it and those who DO modify them are a smaller community -- hell, most everyone I've ever met with a modified Cat or Bird is aware of this site! 

If I ever purchase a fox Mustang myself, you can bet your ass I'll shop around for one who's owner had a clue and not some kid who hacks things to pieces.....  I see them go for top dollar hacked up and running like garbage....


That's kind of why I bought a Mark VII. The engine and wiring was stock. At least I know if modifications get done they will be done correctly and not hacked. You won't believe the things I've seen on 5.0 Mustangs. Plus any Mustang with a BBK "cold air" kit and headers/exhaust is "modded and fast" therefore worth the $5K the guys is asking. Sure.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Aerocoupe on December 04, 2013, 08:40:35 PM
http://forums.corral.net/forums/5-0-5-8-engine-tech/303906-5-0-hard-no-start-when-hot.html

http://forums.corral.net/forums/5-0-5-8-engine-tech/845445-hard-starting-hot.html

Me thinks the ECU has taken a dump?

Darren
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 04, 2013, 09:27:59 PM
To be honest, that's what I'm leaning towards at this point too....

Anyone got a DA1 laying around?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Beau on December 04, 2013, 09:53:58 PM
I don't have a DA1, but I have the equivalent from a Mark 7, if you need one simply to verify the EEC is (or isn't, whichever) is good.

Let me know...I can send it your way in the AM, Paul.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 05, 2013, 08:51:40 AM
I'll take it.  Shoot me a PM.  I'll pay for it and the guy will pay me back.  He lives a few blocks away from me so I know he aint going anywhere, lol.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: flipnbird on December 05, 2013, 07:25:43 PM
If that dont go through, i have a Da1 i will sell you. Came out my bird before i switched to mass air.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: kuchak on December 13, 2013, 02:25:46 PM
My $.02 based on two experiences of rich running Turbo Coupes: It was the FPL which read fine at idle but was dumping in massive fuel when driving. You would need to tape fuel pressure gauge to the windshield and drive it to check. If you know it is rich at idle, then this is not it as you checked FP.

What tells you it is rich? The smell? Exhaust color?

Also, if O2 sensors detect false air like from an exhaust manifold leak, they will try to enrich the mixture.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: kuchak on December 13, 2013, 02:37:37 PM
Quote from: kuchak;425578
My $.02 based on two experiences of rich running Turbo Coupes: It was the FPL which read fine at idle but was dumping in massive fuel when driving. You would need to tape fuel pressure gauge to the windshield and drive it to check. If you know it is rich at idle, then this is not it as you checked FP.

What tells you it is rich? The smell? Exhaust color?

Also, if O2 sensors detect false air like from an exhaust manifold leak, they will try to enrich the mixture.


Sorry, I meant FPR, fuel pressure regulator, not FPL.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Aerocoupe on December 15, 2013, 12:51:41 PM
Have you had time to see if the ECC was the issue?

Darren
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Haystack on December 15, 2013, 10:28:26 PM
I'm curious on this as well.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: TurboCoupe50 on December 16, 2013, 11:02:06 AM
Late to the party but my guess is if it will give expected codes for induced faults the ECM is probably OK...

What I'd do is disconnect both o2 and run it, if the problem changes then maybe a heater is shorted internally causing issues... If that didn't help, disconnect every sensor other than TPS & MAP, the engine will still function reasonably well on only these sensors... If that doesn't do it then wiring or maybe the ECM...

Of course if fuel pressure is high A/F will be extremely rich...

Any chance it has the wrong ECM installed???
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 21, 2013, 07:06:49 PM
Quote
What I'd do is disconnect both o2 and run it, if the problem changes then maybe a heater is shorted internally causing issues
Had him do that early on.  No change whether hooked up or disconnected.....

Update:  He was able to borrow a known good DA1 ECU and swap it in.......  No change.....
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: ZondaC12 on December 21, 2013, 09:33:35 PM
Unless I misunderstand the function of O2 sensors entirely, I believe they are "fine tuning" in a sense. They exist as feedback and thus can't cause an engine's A/F ratio to go *drastically* rich or lean. I'd bank on the ECT, ACT or MAP.

When it's warmed up, does it start better if the throttle is opened any amount?
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 21, 2013, 10:02:16 PM
Not really.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: ZondaC12 on December 22, 2013, 12:07:05 AM
It could totally have a beat starter/bad connections/etc. in addition to the fuel metering issue. Stomping the throttle to the floor and then cranking *does* shut the injectors down, I have confirmed this. A flooded engine can be cleared out doing that.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: V8Demon on December 22, 2013, 09:37:24 AM
Cold crank is perfect.  I was unable to do any work to help him with my injury.  I could only be there and talk him through it when possible.  I think it's my turn on this thing after the holidays......
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: 5.0stang on January 08, 2014, 07:27:29 PM
Hi guys I'm new to the forum figured I'd register.  The car V8demon is referring to is actually mine.  To recap and update here is the car. 87 mustang GT 5 speed T-Top. long tube headers. Off road h pipe Mac dumps. Stock motor.  New dizzy, MAP, TFI, ACT. ECT. TPS.Battery. Starter solenoid. Vacume lines.  Now the car is still running rich. And acting like a dead battery on hot start.  Leaning towards a bad coil killing my tfi ??? I also just got a DA1 out of a running 5.0. And thanks Paul for the post
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: ZondaC12 on January 08, 2014, 09:58:51 PM
Can you confirm the thing charges properly? What is the battery voltage once you shut it down hot? Coil is easy enough to change. Can he lend you the coil outta his cougar/know anyone else with a Fox 5.0? Did you just obtain the DA1 computer or attempt to install it already? If you try another coil, AND the computer, and there's still no change...I guess I'd rip the harness out and look for evidence of critters having chewed wires up...previous owner botching things etc...cause I'm pretty sure you've replaced EVERYTHING!

Is there *any* observable change, any stupid boring detail that seems to act differently once the car has run for 5-10 minutes or so? I am guessing not since as Demon stated, unplugging the O2 sensor harness made absolutely no difference. So it's either not even entering closed loop, or some other externality is so  bad that the comparatively teeny weeny input from the O2's commands no authority. I don't remember...have you checked vacuum? Ought to be 19 inches, I think even 18 would be too low. That's a speed density car so it needs every bit of 19 inches. Personal experience has shown me that 16 inches makes the exhaust smell HORRIBLE and the engine refuses to idle properly for any extended period of time, without opening the throttle manually with the stop screw to help out.

If someone you knew had a scanner that was OBD-I compatible and could watch the computer's signals, you'd learn oh-so-much. The idea has already been tossed out about the Engine Coolant Temperature sensor which you've replaced. I believe that sensor is supposed to provide a variable resistance that the computer measures. Find out the spec on this and replicate it with some RadioShack resistors. You might need to do this for several sensors should you choose this diagnostic route. Somewhere I think you'd find a broken circuit, and the computer is receiving no input, and who knows what it'll do with that.

Does it run "super-duper excessively rich" from the MOMENT you start it cold? Because we can all vouch for starting our car cold and not smelling a horrible rich condition. Meaning that the computer doesn't add THAT much fuel even for a car started at 5 degrees F. It's just not programmed to do that. If this is happening then I say vacuum leak or some disconnect or error between the MAP and ECM causing the ECM to believe the manifold has less than 19 inches of vacuum, which it interprets as throttle is opening, air is rushing in, acceleration is taking place, and extra fuel is needed. Again, I have driven around (another lame-ass long story of stupidity for another day) a 5.0 for 2+ years, running on 16 inches of vac, with speed density, and boy what a pain in the ass. Poor idle, misfiring/stumbling, harsh and rough harmonics in the cold (okay it also had a random unknown mild aftermarket cam, re-read the remark about dumb-ass story) were the order of the day until I found a new daily driver. (But around 3,000 RPM or so she'd really turn on!!! :rollin:)
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: jcassity on January 09, 2014, 09:45:30 AM
connecting zonda comments............

I havent read this whole thread,, but reading it now.

direct copy and paste from my DIY link down below my signature.
INfo taken directly from my shop manuals.


=============================
EGR/emissions solenoids (codes)
Dual Thermactor Air control Solenoid Valve- both should read 51-108 ohms
EGR Solenoid Vacuum Valve Assembly - both should read 32 to 64 ohms
EGR Valve Position Sensor EVP (OR/W to brn/ltgrn resistance is 5.5k with no vac and 100ohms with vac)(4-6vdc on VREF or/wht)
Electronic Vacuum Regulator EVR 30 to 70 ohms (koeo voltage is about 10.5vdc)

============================\
EGR test and EVP sensor test
apply vac pres to egr vac line fitting.
if it holds the diaphram for a long time,, the diaphram is good
remove carbon buildup on egr base as well as egr base plate assy for 3.8l engines

EVP test (egr sensor)
wire id...
EEC PIN 26 "VREF" orange/white (parallels off to map)
EEC PIN 27 "EVP SIGNAL" brown/light green
EEC PIN 46 "SIG Return" black/white (parallels off to self test conn)

disconnect vac line
disconnect elec conn
hook ohm meter up to the VREF adn EVP Sig contacts
hook up vac guage or apply vac to egr
ohm meter should start out at about 5.5k ohms.
as vac is increased to max, resistance should bottom out to no less than 100ohms.

key on, engine off
cap off vac fitting on evp sensor
measure for 4 to 6 volts dc between VREF and SIGNAL RETURN (ground)
______________________________
ECT sensor test feeds the computer
Resistance test pin to pin of the sensor (this is a variable resister proportional to temperature including outside air temp if the motor is cold)
at 50degF=58K ohms
at 65degF=40K ohms
at 180degF=3.6K ohms
at 220degF=1.8K ohms

next clean the end of the sensor with scotch brite ect and retest
if high temps persist, replace coolant temp sensor and ECT as a matched set.
if that does not work, start looking at your coolant system parts.
----------------------
ACT sensor test ,,,feeds the computer
Resistance test pin to pin of the sensor (this is a variable resister proportional to temperature including outside air temp if the motor is cold)
at 50degF=58K ohms
at 65degF=40K ohms
at 180degF=3.6K ohms
at 220degF=1.8K ohms
=============================
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: thunderjet302 on January 09, 2014, 03:57:49 PM
Quote from: ZondaC12;427008
Does it run "super-duper excessively rich" from the MOMENT you start it cold? Because we can all vouch for starting our car cold and not smelling a horrible rich condition. Meaning that the computer doesn't add THAT much fuel even for a car started at 5 degrees F. It's just not programmed to do that. If this is happening then I say vacuum leak or some disconnect or error between the MAP and ECM causing the ECM to believe the manifold has less than 19 inches of vacuum, which it interprets as throttle is opening, air is rushing in, acceleration is taking place, and extra fuel is needed. Again, I have driven around (another lame-ass long story of stupidity for another day) a 5.0 for 2+ years, running on 16 inches of vac, with speed density, and boy what a pain in the ass. Poor idle, misfiring/stumbling, harsh and rough harmonics in the cold (okay it also had a random unknown mild aftermarket cam, re-read the remark about dumb-ass story) were the order of the day until I found a new daily driver. (But around 3,000 RPM or so she'd really turn on!!! :rollin:)


Are you sure about a stock 5.0 HO needing more than 19" of vacuum to run right? My stock 91 Mark VII makes 18" at hot idle and runs fine. Most stock 5.0 HO engines I've seen make 17-19 inches at hot idle. My Thunderbird makes 17" at hot idle.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: TurboCoupe50 on January 09, 2014, 10:13:28 PM
Quote from: thunderjet302;427036
Are you sure about a stock 5.0 HO needing more than 19" of vacuum to run right? My stock 91 Mark VII makes 18" at hot idle and runs fine. Most stock 5.0 HO engines I've seen make 17-19 inches at hot idle. My Thunderbird makes 17" at hot idle.


I'm gonna agree, idling 17/18" is plenty of vac...
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: ZondaC12 on January 09, 2014, 10:22:03 PM
Hmmm. Forget that then. Someone must have blurted that out at one point and I latched onto it. I feel like 19 sticks in my memory on multiple ocassions. I'll have to test the red cougar and the daily...

In that case maybe the Vic wasn't *that* bad then. Or maybe one inch makes a big difference.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: Clayton on January 12, 2014, 01:39:17 PM
All stock? Not doubting anyone at all maybe were not thinking primitive enough. Timing chain.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: ZondaC12 on January 12, 2014, 05:29:54 PM
That would sure suck!!
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: 5.0stang on January 14, 2014, 10:23:09 PM
Ok new stuff to add to the list of things I've tried. I took a computer out of a running 87 fox DA1 same issue so I know my ecu isn't bad.  Going to pull my dizzy and make sure its in the right tooth.  previous owner replaced dizzy and may have placed it in wrong. Going to exchange TFI ( 5th time now... )  get a new coil and IAC. I haven't checked how much vacume it's making but I tried the " carb cleaner " trick around the intake gaskets and vacume lines. No change in rpm. Fuel pressure is within its parameters. Tps is set at .8 timing is set at 10* BTDC
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: 5.0stang on January 14, 2014, 10:29:58 PM
I've also taken apart harness nothing chewed or cut. All fuesable links are intact ( equal voltage on both sides ) I'm driving my self nuts. I've worked on these cars before and I've never encountered this. When I first start car its not rich. Once the idle drops and evens out that's when it becomes rich with visable smoke from tail pipes ( greyish not white or blue )

In the mean time I will be continuing the GT to  LX  conversion.
Title: 87 Mustang 5 speed running really rich hard start when warm....
Post by: TurboCoupe50 on January 15, 2014, 12:55:38 AM
Have you subbed the MAP??? (If so I missed that)

One thing not mentioned is disconnecting alternator and run just on battery... There have been issues with 2G alternators that have a open RF suppression capacitor or leaky diode(s) that caused all sorts of driveability issues with no codes set...