Hello foxbody Thunderbird and Cougar enthusiasts. I'm a newboy here, I just got an '88 Thunderbird 5.0 with a 5 speed swap and only 82k miles on the odometer. I've been trying to soak up the knowledge that is here on the site (Lots of good info).
But I have a problem that I can't find a solution for: My Tbird has an intermittent miss that I can't quite find the cause of. When the engine is cold, it seems to run rather well, but once it warms up, it starts missing badly and will stall when I come to a stop, but it won't usually stall right away, it will run for about 10 seconds while stumbling, then just cut out. It always starts up right away afterwards though with no problems, and sometimes runs great again for about 30 seconds.
I pulled the codes, both KOEO and KOER show a code of 34, which appears to be an EGR sensor problem, but the EGR and the sensor both appear to be functioning correctly. I also checked the IAC, TPS, plug gaps, firing order, ignition wire condition, cleaned the salt and pepper shakers (which did seem to help, but probably isn't the cause of the problem), and searched hard for a vacuum leak, but found nothing.
Also, if I can trust the previous owner, he replaced the distributor, cap and rotor, plugs, wires, TFI module, PIP sensor, fuel filter, fuel pump, fuel pressure regulator, O2 sensors, and entire exhaust system. It's now running Factory tube headers, Mustang H-pipe, long glasspacks, and no tail pipe.
I'm starting to get stumped, and I'd rather not start throwing parts at it yet. Any idea on what the problem could be?
Sounds like the way mine acts with my O2's hooked up....only mine won't start though.
If you've got a known good EGR, put it on, test it, and pull codes again, although there may be memory codes stored in the eec yet. I think it takes 40 engine start/off cycles to clear them once resolved. May be wrong...
BTW, welcome aboard!
Thanks for the welcome, it's good to be in a place like this.
I don't have a known good EGR, I don't have many 5.0 parts sitting around. Although, I found an alternate definition for the code: EGR Valve Position/Pressure Feedback EGR Voltage Above Closed Limit. If that's what is happening, then my EGR sensor might be shot. The EGR did seem to close completely, but that doesn't mean the sensor is reporting correctly.
Maybe I need to unhook the battery to clear the codes before I trust that diagnosis too much though.
When do you get the code 34? KOEO, Memory or KOER
You don't have a pressure feedback sensor.
You have a position sensor.
Code 34 says the sensor voltage is too high for the closed position.
If the code is KOER, disconnect and plug the vacuum line to the EGR valve.
Does the 34 change to a 33?
To clear memory codes, unplug the STI to SIGRTN jumper while the codes are reading out.
Also, try running it with the spout unplugged. If it runs better with the spout out, it puts the computer into a fail safe mode that will ignore all but the most important sensors. You could also test several different things to test if its spark or fuel related.
I saw the 34 code twice on the KOEO test, so I guess that means it was a hard code and a memory code. Then I saw it again on the KOER test.
I didn't think to try disconnecting the EGR, that'd be a quick test to show if that was the cause.
When I get home, I'm going to reset the codes and run the tests again to see if it reappears or reappears without the vacuum line plugged in.
Thanks for the ideas.
Will do. I don't think it really helped smooth the engine out when I was adjusting the timing, but I didn't try it for very long either.
I reset the codes, run the KOEO and KOER again, and got the 34 code again right away. Then I unhooked the vacuum and plugged it, cleared and did the tests again, got the same 34 both times. Seems to me like the EGR position sensor isn't reading correctly. The big question is: Could this cause the missing and stalling I'm seeing?
I tried a test drive with the SPOUT removed, it ran almost perfectly. The only problem was some slight stumbles, but that might be from dirty injectors, as it has sat for a long time. What sensors does the computer ignore when the SPOUT is taken out? It seems like the problem is one of the deactivated sensors.
Also, looking through my notes from the test, I had a code 21 fault from the KOER test. That's pointing towards a coolant temp sensor, which would make complete sense. If it were reading wrong when the engine warms up, it would be shoving extra fuel into a warm engine that doesn't need it. Also, I'd be willing to bet that the ECT is a sensor that is ignored when the SPOUT is removed.
The ect will cause some codes and cause some other problems.
To be honest, I'm not completely sure what sensors are eliminated, so I'll look through some notes and see if I can find anything. Here is a "simplified verson of how efi computers work"
http://oldfuelinjection.com/?p=64
Here are some testing procedures to do when you have a no start condition. It is still failing to stay running right? If so, this should help you pin point your problem.
http://sbftech.com/index.php/topic,588.0.html
I would personally ignore the egr as long as you know it is in the closed position. As long as you have a code for it, the computer automatically deletes its function anyways.
Also, run a blance test according to this. (Scroll down a bit)
http://sbftech.com/index.php/topic,2471.0.html
I finally have time to update.
I did perform a balance test, the result was a 9, and there was no other clues that it was a specific cylinder related problem.
I tested vacuum with a gauge, I get a solid 20in at idle with the SPOUT out, and a wavering 19-20in at idle with the spout in. The vacuum changes seem to mirror the speed of the engine, so I didn't read too much into the non-steady reading.
I replaced the coolant temp sensor, it made sense and it did throw a code, but the new one didn't help the missing and stalling condition.
After all of that, I decided to double check my timing. I set it to 10degrees, then checked the timing with the SPOUT in for the heck of it, and that showed something interesting. The timing at idle with the SPOUT in is around 24 degrees according to my timing light, but it is not steady. When the engine feels like it's missing, the timing will retard by about 5 degrees, but then will go back when it recovers.
Is the timing the cause of my issues, or is it a side effect from whatever is wrong?
Its normal for the timing to bounce around with spout in, even at idle. The sput basically allows the computer to change the timing.
I suggest you try checking the tfi, and spark output.
Put the timing light on your coil wire and see if it starts to miss spark while its running rough or missing. Does it do it with spout out at all? Just curious, not sure if it would even mean anything.
The ballance test tells us its not a fuel or compression problem, now we have it narrowed down to spark. Doing the tests in that sbftech link for a no start, you should be able to follow all of the testing procedures for no spark and go from there.
Let us know.
Ok, so the timing is probably changing because the engine is slowing down.
Checked the TFI, it passed all the tests with a Ohmmeter. Checked the spark output, I get a fat blue spark from the coil and from a plug wire.
Then I started going through the No Spark tests on the link, the only one that showed anything was when I put the light on the Negative coil wire and rotated the dizzy, the light dimmed. The test said if the light blinks, replace the coil, but I didn't git a full blink, just a dimming. Not sure if it's notable or not.
Then today, I set the base timing to 20 degrees, then removed the SPOUT. I wanted to be sure that it wasn't just the base 10 degree timing that was making the engine run well. On the drive to work, it still has an idle that is a bit rough and stumbling, but it never stalled and it never cut out at cruising speeds. That seems to tell me that even if it is a weak coil, it's not the cause of my cutting out and stalling.
I didn't have a chance to put the timing light on the coil with the SPOUT in and the engine missing, but it didn't miss a beat with the spout out and the engine stumbling at idle.
As I was driving it today, I noticed something. I'm getting horrible gas mileage. I put 90 miles on this tank, and I'm nearly down to half.
That got me thinking... What if the problem is a clogged return fuel line? That'd cause higher than normal pressures at the fuel rail, would affect all cylinders, so it wouldn't show up on a cylinder balance test, wouldn't show up in the codes or on any electrical test I've been doing, and wouldn't have been fixed by any of the parts the PO installed. I'm not sure how the SPOUT would affect it, but it could be a contributing factor at least.
It makes sense to me anyways, I know the car has sat for a long time before the PO had it.
That is insane fuel consumption....... maybe injector hanging open?
What dos the map sensor read voltage wise at idle? There is a way to test its output based on vac pressure.
If your fuel pressure was cruddy, the o2's should throw a code. If the map sensor is bad, it goes into a fail safe (limp mode) and should also throw a code. If you have the ability to read fuel pressure, it would be a good idea too.
If you have a bad leak in your vac line to the map sensor, you'll get about 5mpg and leave black soot under the tail pipe, staining the ground.
I got some more time to putter around with it tonight, and there is a huge miss visible on the timing light right off the coil with the SPOUT in and warmed up. When it's cool, or when the SPOUT is out, there is no discernible gap in the light, so it at least is producing enough spark to trigger the timing light then.
What exactly does that point to? I suppose the PIP should be ok, because it's output isn't SPOUT dependent, so most likely a TFI module that goes bad with heat? They tested ok with the Ohmmeter, but that was when they were cold. They're both aftermarket too, so it's possible they could have failed in a manner that I'm not familiar with.
I don't have a fuel pressure gauge yet, but I did unhook the fuel return and blew through it with some very low air pressure from my compressor, it bubbled in the tank quickly, so there's not likely to be a problem there. Just a theory that was fairly easy to check.
As for possible vacuum leaks, I got a strong reading of 20in at idle at both the brake booster and the MAP sensor. I didn't test voltage at the MAP because I read that its signal is a frequency signal, and my meter can't read frequencies.
That is entirely possible. I'm guessing that I have a multiple cause problem here, it has sit for a long time, which is why the mileage is so low, but it's also possible to have varnish build up in the fuel system. I'm running some injector cleaner through it, but it probably won't help very quickly.
I'm not too worried about the injectors though, I'm planning an HO (or similar) swap.
Get the car to operating temperature -- when your issue starts -- and shut it off. Disconnect the o2 sensor harness from the engine harness. Restart and let it run for a few minutes.....
What happens?
Well, I'm not sure where to go from there. I don't know enough about what changes are ddone spout in or out to tell even what sensors are being used. The computer will turn off adaptive strategy with the spout out. It has to be caused at least partially by the output of a sensor if it runs fine cold/spout out. Electronics fail much easier when there warm. Autozone will test the tfi, but make sure they run it a couple times, to get it warm.
Try unhooking the o2's like paul mentioned.
Have you checked ground resistace betwee block and neg post? How about sigrtn and neg post? A bad ground to the eec could trip up certain sensors, giving the computer odd spikes. A weak ground acts just like bad or overheating electronics. As the load becomes too much for the ground, it will start to lose continuity, then that can releive some of the load on the wire, giving it a weird random almost on off stumble.
Looks like the missing isn't completely temperature dependent. I started it up yesterday, and it was missing from the coil right away. I let it run until it eventually stalled, then I tested the TFI again to see if it failed when hot. All tests were exactly the same as when it was cold, so TFI can probably be ruled out.
After that, I went around and removed and cleaned all the grounds I could find, including the computer ground in the kick panel. After that, I started it up again, and while it still wasn't running perfectly, the timing light showed absolutely no missing at the coil, even after I took it for a 15 min drive to make sure it was completely warmed up.
Then, unhooked the O2 sensors to see what would happen. No check engine light came on (I didn't check the codes afterwards though), and while it seemed to run a little bit worse, it didn't run any better when I pluged the 02 sensors back in. I hooked up the timing light again, and I found the missing was back.
When I hooked the TFI back up after the test, I messed with the wiring a little bit, and then I had to tug on the wiring a bit again when I unplugged the O2 sensors, so I'm thinking I might have a problem in the wiring behind the upper intake there. I'm thinking the PO had the upper intake off for some reason, so it's possible he accidentially crushed a wire or something back there. I think the only real way to check is to take the intake off again and look at those wires closely.
Yea Joe! I have nothing to contribute to this thread except to say I'm glad you are here and posting. Hope you get this sorted.
For everyone else, Joe and I went to college together and he even helped me wrench on the old cat a few times. I still remember changing the water pump…with the assistance of a dental pick found in the front air dam. Good times.
I have no idea why there was a dental pick in your air dam, and I have even less of a clue why it was so helpful for us, but I do know we couldn't have changed the water pump without it. One of the strangest car repair stories I've ever experienced. Pretty trustworthy, that SSX, but at least we did end up repairing his Cougar. (It was a sweet car too.)
No updates on my Thunderbird yet, the Wife and I were out of town all weekend, so I didn't get a chance to do anything. Not sure if I have time to remove the upper intake tonight, but I'll poke around in the wiring harness to see if I can make it change moods.
Let us know what happends. I hope we can all learn from this.
I'll be sure to post the culprit when I find it, I'm always annoyed when I'm searching for similar symptoms and they never tell what fixed it.
Just stopping to think now... The spark seems to be a major part of the problem (probably not the entire problem though, but let's start somewhere.) The only things that really control the spark are the PIP, TFI module, computer, coil, and all the wiring in between.
Now, the problem is somewhat temperature dependent, it gets worse when the engine warms up. So, it seems unlikely that it is the computer, as it doesn't get any of the heat from the engine bay. The PIP and TFI don't seem very likely, as I have swapped them for a different set. There's no guarantee that either set is good, it seems unlikely that both have failed in the same hard to detect manner. As for the wiring, it seemed like all my poking and moving of the wiring last night made no change. If it was an intermediate short, I think I would have had some effect.
That just leaves the coil, which seemed to test a little weak during the "no spark" testing. It also is subjected to engine heat and wouldn't be affected by manipulating the wiring. I measured the resistance over lunch, and I'm getting 0.3 on the primary and 8 kohm on the secondary, which is right on the low end of what's acceptable (according to the specs I could find). When I get a chance, I'll check it when it's warm to see if that makes a difference, or I could take it to a advance or oreilly's to see if they'd test it.
Joe , Please check your pm I sent you friend. :poke:
p.s. my :2c: worth
I have a spare EEC that you are welcome to try to rule out the computer as a suspect.
I'm going to get a new coil tonight, but if that doesn't work, I'll take you up on your generosity. Thanks for the offer.
I probably have a spare coil you could try too if you want me to check.
If you were closer than Offut, I'd consider that too, but we live about as far north as possible in Omaha (Ponca hills area), so it wouldn't be a quick drive.
There's one at Oreilly's for $18 that should be good enough quality to let me know if it's the problem or not, and I think I'll get a new air and fuel filter while I'm there too.
But again, thanks for the offer. I get the feeling that It'll be nice having a knowledgeable person in the area.
Finally, some good news. I got the cheap coil, put it on, and immediately fixed the missing. Took it for a drive, and there was no cutting out, no stalling, no obvious missing. Progress!
Though it still stumbles occasionally, most notably when you're cruising along and let off the throttle. It feels like the engine shuts off for a fraction of a second, and tends to make the car jerk. Other than that, it's got a slightly lopey idle and it still smells a bit rich. I'm guessing it's a fuel problem, probably gummed up injectors or a plugged fuel filter.
But first things first: A victory beer. Huzzah!
first thing I do with every car I buy is the fuel filter. I have never replaced one with even slightly clear fluid in it.
My buddies thunderbird was losing fuel pressure, and it ended up being the fuel filter being rusted out. When we swapped it, black tar like came out and stained the ground. Ran a lot better, reved quicker. Mostly I have noticed a very slight increase in mileage per tank, and better throttle response. As far as I can tell it hasn't really effected power.
Time for that h.o. swap now that you got it running good. Throw some newer/rebuilt 19#ers and h.o. cam.
The previous owner said he changed the fuel filter, and while I'm sure he did, I'm not sure if it's still clean. After all, the car has sat for a long time, so it's still probably pulling up from the tank.
Other than that, the injectors are probably a little gummed up.
Of course, going for an HO swap would easily fix that... But I'm also considering just getting a Moates Quarterhorse and keeping the non-HO firing order. I'm not sure which way is better or easier or cheaper or more powerful, but I haven't planned that far ahead.
Though, I do know my friend has some truck heads he'd be willing to part with and I already have the HO upper, so I have a source on some good parts already.
Plugged fuel filters are a real ISSUE in my view but the engineers dont see it that way. And the new cars have them in the TANK. Happy DAYS. Drop the tank or remove the access plate to service. And the engineers claim they are lifetime filters. I have seen filters plugged to the HILT and some engines run fine for the most part. But i am in favor of regular fuel filter maintenance As stacks points out . +1
Note a bad coil is not that common on fords TFI SYSTEM. Other than the aftermarket JUNK COILS BY MAJOR COMPANIES!!! Always use MOTORCRAFT OEM. But a quick run on the DYNE with the cylinder scope would have picked that up in a second. Also resistance readings are a waste of time when shooting coil issues. I know i will get push back from this statement. Also a poorly tuned TFI system plays havoc on these systems and takes it toll in TFI modules and components. The tune must be spot on or the system will eventually FAIL
:burnout:
Ony way a filter can last a lifetime is if it dosen't filter anything.
High performance coils produce more voltage than plug wires can handle. Best to use factory coil.
Some 87's have plastic timing chain gears.
Do the h.o. swap. I picked up an h.o. cam for $20 from a stang guy, upper for around $20, exhaust "headers" and an h-pipe for about $100, and the stang sd computer for about $50 if I remember right. This should get you from 150 hp, to about 225.
Changed the fuel filter last night, I didn't see any crud come out of it when I let it run out, and it didn't really change how it runs. Oh well, cheap insurance.
It sort of feels like there might be a dead spot in the TPS now. It only seems to cut out when I lift off the gas slowly, when I just drop my foot off of it, it'll slow down without any missing. Not sure if that could also be causing the rough idle too, but at least it's good enough to drive now. Also worth noting, it doesn't smell anywhere near as rich as it used to. Still a little bit rich, but I'll figure that out eventually.
Also, last night I messed around with the clutch cable, I routed it beside the engine mount instead of under the k-member, and I also shot some rem-oil in it to help it slide freely, and it has made a world of difference. Before, it was stiff enough that my leg was actually sore after a day of driving. Now it feels very springy instead of grinding.
Haystack, you're starting to talk me into doing the HO swap instead of the other way. I already have the HO upper, a free flowing H-pipe, Mustang HO style tube headers, and a source for the 87 and up style HO heads. I'd just have to find a speed density computer from '87.
I still have the injectors if you want them. Does Erin still think it's a pimp-mobile, or is she coming around?
Ya know, I'll take the injectors. Let me know what you want for them and shipping (Unless you're coming down to Omaha anytime soon... Or, I guess we have a trip to Owatonna next month... or whatever else would work...)
I haven't made her ride in it again yet, so I doubt she's changed her mind much. I bet some "de-ghettoification" would be helpful too. It'll look better after I fix the fender and find a new lens for the marker light on the front. Oh, and the blurry tint needs to go too, it's annoying.
Oh, one more weird driving quirk I noticed today. Whenever I turn hard (or powerslide...) to the right, it will cut out shortly after. I'd bet it's fuel sloshing around in the tank causing it, but I've never experienced that before in any other Fox. Maybe when I get near the bottom of the tank, I'll drop it and make sure the pickup is fully submerged.
Baffle in the tank may have broke loose. Common issue with the Mustangs and the Birds. If you drop the tank double check the sock on the inlet side of the FP.
Darren
That kinda what I was assuming, though I wasn't sure there was a baffle in there.
Easy diagnosis, not so easy to crawl under it and fix it...
My buddy's stang had that same issue,baffle broke. New tank all cured.
Joe, I can send it or I can meet you guys somewhere when you come up, I'd like to see you guys anyway. We can meet in Sioux Falls or something if you don't want to come all the way up here. Hit me up on Facebook whatever you want to do. I'll just give them to you. If you want me to ship them, I'll just charge you shipping. I don't know when my next trip to Nebraska will be.
I finally found the time to drop the gas tank. It turned out to have a lot more gas in it than I thought... It was touching E when I parked it, but it still had at least 8 gallons in it. It was a pain, but I dumped all that out and transferred it to my Mazda just so I could work with an empty tank.
I did find the problem though. The baffle was still mounted solid, no problem whatsoever there. The fuel sock was missing though. It's not in the tank anywhere, so I'm betting that the previous owner that was proud to have changed the fuel pump didn't bother putting a new sock on it.
So, tonight I'll get a new sock, and I'll have to get some gas too... I didn't think to save a gallon or two to put back into it after I reinstall it.