Still running lean

Topic: Still running lean (Read 10077 times) previous topic - next topic

Still running lean

January 13, 2009, 10:44:20 PM

Sp apparently after having the entire engine looked over, nothing big is standing out. Lifters were put back to stock FMS while the lower intake was off and the valvetrain is back quiet again but all new gaskets installed, egr and iac blocked off to check for internal problems, yet the engine still doesn't run right. Timing verified at 10 degrees, cylinder blowby test/crankcase pressure showed a max of 4cfm on 5500rpm snapped throttle runs. Car looked over by a performance shop and a machine shop that also has their own dyno. Oxygen sensors are switching normally but a wideband shows way lean when the engine is running poorly.

37psi fuel pressure, yet warm open loop runs incredibly lean. The popping through the intake is gone but the engine falls on its face in warm open loop for a second or two before it always corrects itself. Car has the mass air conversion done which helped nothing. Vacuum is at 16in at warm idle, idle shakes the entire front clip in warm open loop - smooth as the stock SO motor in closed loop. Fuel economy is still down at 28mpg compared to the previous similar motor that gave me 30-31. Other motor also ran incredible all around compared to this one which runs like the 225,000 mile SO motor it was supposed to replace when in open loop. Plenty of power in closed loop though. TPS, ECT, ACT, MAP/BAP sensors new, mass air sensor as clean as it'll ever get.

Anyone have any ideas on where to look next? I have a wideband coming so I can monitor this more closely myself but I am out of ideas, as are both shops. The shops tell me to just get it tuned for more fuel in open loop but that isn't a cure...

Still running lean

Reply #1 – January 13, 2009, 11:46:32 PM

Sounds kind of like the same problem I had with my 1988 Cougar XR-7 after I converted it to Mass Air. After months & $$$ later of trying to figure out what's wrong with the engine, I found out that you have to get an air adjuster. Which is a DIGITAL ELECTRONIC solution that allows you to adjust your air-fuel ratio rich or lean, to accurately match the Mass-Air Flow Sensor calibration to your engine. The Air Adjuster gives you the adjustability over the air/fuel ratio that you don't currently have on late-model, computer-controlled engines. Eliminates rich/lean conditions, hunting/surging idle and drivability problems resulting from a mis-matched Mass-Air Flow Sensor signal. Go to mass-air.com to get more info & you can purchase the Air Adjuster there for $179. Hopefully this helped.

Still running lean

Reply #2 – January 14, 2009, 12:06:59 AM

Here's a question but what's your fuel pressure? Also what injectors are you running? 19s or 24s? What MAF are you using?

Still running lean

Reply #3 – January 14, 2009, 12:26:03 AM

Quote from: Seek;251574

37psi fuel pressure

When running with the vacuum line disconnected. 19lb injectors with a stock 55mm mass air meter and 60mm throttle body. Fuel pressure isn't 40, but its within spec and shouldn't be causing this problem at idle.

Still running lean

Reply #4 – January 14, 2009, 07:49:02 AM

I know you said problem continues since switching to mass air, but your issue sounds similar to Ronnie's(chrome302jr)problem...

(BTW he's fine and still has his Bird, just has other things going on in his life)

Anyway he had some very lean issues(18:1 on wideband) and it stumbled badly... He had tried about everything else, so we tried my MAF with no help... Finally tried my A9P EEC(believe his was same), which fixed it... Soooo if you can borrow a EEC, may want to try that...

Also Paul posted recently about a continual rough running issue and had found the o2 sensor wires were reversed(right to left bank)...

Still running lean

Reply #5 – January 14, 2009, 09:02:16 AM

I'll find one and give it a try (Mine's an A9P also). I don't see why oxygen sensors being crossed would affect open loop though. Is there even a decent way to know which goes on which side without trying to just keep them separated when initially pulling the motor?

Still running lean

Reply #6 – January 14, 2009, 08:34:22 PM

Is your car a stock 5.0L or do you have some high performance parts? My cougar is stock other then shorty headers & when I converted it to Mass Air the engine started to spit & sputter & hesitates when you push the gas, like ther'es a vacuum leak. And it has a rough idle. The company i bought the Mass Air kit from said the conversion kits are for HO motors and that I needed to get an Air Adjuster because the Mass air kit is set up to read signals for a HO motor & that is why your car is runnin to lean or to rich. And the Air Adjuster allows you to adjust your air-fuel ratio rich or lean, to accurately match the Mass-Air Flow Sensor calibration to your engine. The Air Adjuster gives you the adjustability over the air/fuel ratio that you don't currently have on late-model, computer-controlled engines. Eliminates rich/lean conditions, hunting/surging idle and drivability problems resulting from a mis-matched Mass-Air Flow Sensor signal.

Still running lean

Reply #7 – January 14, 2009, 09:48:46 PM

why would you convert a stock car to mass air?

Still running lean

Reply #8 – January 14, 2009, 09:57:17 PM

Quote from: 88cougar;251676

My cougar is stock other then shorty headers & when I converted it to Mass Air the engine started to spit & sputter & hesitates when you push the gas, like ther'es a vacuum leak.

I'm confused about all this - how does this car even run? Mass air requires a mass air computer. The mass air computer is setup for the HO firing order. The HO firing order would not work with the SO's camshaft. Therefore, there is no way this engine could run with the stock camshaft that came in these cars.

I'm also not sure what this "Air Adjuster" is supposed to even do. As long as the mass air meter is setup for the correct injectors, no changes need to be made to the mass air setup since it is typically far more accurate than speed density setups. Unless your mass air sensor is dirty (the big culprit being oil from a reusable air filter), it shouldn't matter. It sounds like you are attempting to use the mass air with the stock 14lb fuel injectors?

If you actually did move to a mass air ecu, at a minimum you had to have installed the HO cam and 19lb fuel injectors. If either of these are missing, there's your problem.

As for my problem, most people wouldn't notice the issue as its only noticeable for about 30 seconds during normal drives. The nuisance is after going into a store, coming back out, and being in a rough open loop again for a minute or two. Warm open loop rough, cold open loop great and smooth, closed loop great and smooth.

I'll be doing a leakdown myself here soon since I don't have 100% faith in any of the shops I've had my car at - I get people telling me different things at different shops, all canceling each other out.

Still running lean

Reply #9 – January 14, 2009, 10:05:46 PM

The parts as they are right now:

Block: .030 over on standard block. .0045 piston to bore clearance with file to fit rings (have to look up the ring gap - think it was like .022 and .026 or something). Clevite 77 bearings. Other usual machine work that came to $800.
Camshaft: 89 Mustang GT - 0 degrees advance/retard
Mass air sensor: 89 Mustang GT
ECU: E9P
Heads: GT40P 00 Explorer 5.0 with Trick Flow "stock replacement" springs, lapped valves as we couldn't verify the seats being cut and 93 Mustang Cobra/Crane Energizer 1.7 roller rockers. Milled for flatness.
Valvetrain: FMS Stock-type lifters, Stock 6.258" pushrods with no shims
Intake: 93 Mustang Cobra
Headers: FMS Stainless w/standard FelPro gaskets (copper leaked badly...)
Balancer: Pioneer SFI 50oz
Exhaust: Dual 2 1/2" with high flow catalytic converters, x-pipe, flowmaster 50 series lers
Transmission: '03 4R70w with Baumannator TCS

Computer codes 94,44,33. EGR code stayed after EGR valve replacement. Thermactor removed. 5in of Vacuum placed on EGR causes engine to stall at idle so it functions properly.
Cylinder balance test code 90 - PASS

Timing set to 10 degrees base
New TPS and sweep checked - 0.98v at idle, 4.68v WOT, 0.90-4.58v at the ECU
New MAP sensor open to atmosphere
New ECT and ACT sensors
Ignition Coil has around 2,000 miles
Distributor cap has around 3,000 miles
Distributor/TFI has around 100,000 miles
Spark Plugs have around 50 miles
Spark plug wires have around 800 miles
Mass air sensor has around 100,000 miles - cleaned
Idle air controller has around 225,000 miles - clean and tested to work correctly
Cloyes "True double roller" timing chain has around 800 miles

Felpro engine rebuild gasket kit - silicone lower intake gaskets at front/rear. RTV used around water ports on lower manifold gaskets and between it and cork. New upper/lower gasket as of last intake pull. Vacuum has standard fpr, vacuum tree, passenger fender and single press in fitting going to PCV valve. Charcoal canister hooked up to vacuum post on front of intake near throttle body runner. Old MAP sensor vacuum port is plugged off on the intake. All new silicone hoses with one standard vacuum hose going to charcoal canister and standard going to vacuum tree.

Entire build has ~800 miles now.

Still running lean

Reply #10 – January 14, 2009, 10:20:12 PM

In order to do any modifications to you engine that are air related you have to convert from speed density to Mass Air to get the full potential of that part. Such as better Intake, Cold air, etc.. I plan on doing some modifications to my engine & that is why I converted to Mass Air. As for Seek you are correct in the fact that Mass air requires a mass air computer. A Mass Air conversion kit comes with a A9p computer depending on if you have auto or man. trans, Mass air sensor, mass air meter, wiring harness, & instructions to install everything. You don't necessarilly need to have a high performance cam to convert to mass air. As long as your sensor is calbrated correctly to your cars setting (which is what the Air adjuster does) your car will run fine with it's original stock motor & fuel injectors. Like I said before, the company I bought the Mass Air kit from said " If you have a High Performance motor or plan on making your stock motor into an HO, the Mass Air sensor does not automatically calibrate itself to your engine. If you don't understand or if what I'm saying makes no sense then go to http://www.mass-air.com & they will explain it to you.

Still running lean

Reply #11 – January 14, 2009, 10:23:58 PM

Hey

I see you have replaced the ign module. Have you swapped the dist or is it the orginal??
Sounds to me like the Stator/Pick up coil in the dist is breaking down
when the car get warm.
I would replace it with FORD or Motorcraft parts. Have used most
aftermarket manufactors and they only work about 6 months before
the break down?

Had it happen to my 5.0 ranger,Black EFI 5.0 cougar and My turbo 351 Cougar.
PS Avoid MSD dist they have JUNK CHINA electronics

Still running lean

Reply #12 – January 14, 2009, 10:49:48 PM

The coil was due to the original stock one having lower than ideal voltage a year ago. The distributor was swapped for the lower mileage mustang one as my stock one started "whining" - I didn't want it to seize up so I swapped it. I would think ignition if it wasn't for the fact that it clears up the second that it goes into closed loop and that the first motor that we put in ran excellent with the same parts other than the new heads, exhaust, and transmission (not to say something didn't "break" in the 6 months the parts were lying around in the garage).

I won't use aftermarket distributor electronics. If I start throwing more parts at it, the distributor electronics will be the first to get moved up to new status.

Still running lean

Reply #13 – January 14, 2009, 10:57:33 PM

Quote from: 88cougar;251699

In order to do any modifications to you engine that are air related you have to convert from speed density to Mass Air to get the full potential of that part. Such as better Intake, Cold air, etc..

As long as there is good vacuum (non-aggressive cams) and no need for huge injectors, speed density works great. Once you need larger injectors, it loses some appeal though. Mass air isn't necessarily needed (it should help open loop...) with minor mods to the intake and heads. Oxygen sensors help speed density compensate a ton, and it doesn't run as overly rich as mass air to get a stock setup a little more power.

As for the mass air, this "air adjuster" I can see helping it work around incorrect fuel injector size but I don't see how you would manage to run a computer on a camshaft that has a completely different firing order. If anything, the engine would shake horribly and be igniting out the intake/exhaust due to improper camshaft timing. Moving spark plug wires around would lessen this but I don't understand how you could have an A9P working with the SO cam.

I only had the mass air parts for future tuning abilities and while they're known to run more rich, they're also known to give you better economy (aka efficiency which means power). I put them on when I had a bad open loop issue with speed density. With mass air the problem remained, but I gained a delayed throttle response...

Still running lean

Reply #14 – January 14, 2009, 11:02:51 PM

About mass-air.com, they are who I got my harness from and I see their "adjuster" but again, that thing's just a bandaid. I see how it works and what its for but the whole "Changing Injector Sizes" thing throws out all credibility. With the correct mass air sensor, this isn't a problem. Anyways, for the price of that thing, I'm halfway to a second hand TwEECer R/T. I have the AEM wideband setup coming that will be installed the week after next.