Been sitting, wont idle.

[TurboLs1]

Finally got the transmission back in my '96 Cobra. The car has been sitting for about 2 or 3 months. I started it and moved it around about 3 weeks ago, and it idled fine, I let the a/c cool off the car etc. Within the last 3 weeks, I have been slowly swapping the trans, it took a while due to doing it by myself and only having one jack, and school.

Now, when I start the car, it starts up fine, tries to idle for a second, then dies. If I use the throttle to keep it running, it starts missing VERY bad after a second and starts smoking me out from running so rich. If I rev it up to about 3k, it will clear up, but fluctuates up and down.

Currently, engine/fuel mods include T67 turbo setup, Accel coilpacks, 42# injectors, Walbro intank pump, Cobra C heads, Mach1 intake, and Diablesport MAFia.

Any ideas on where to start looking? Thanks in advance for any suggestions.

 

[wmburns]

Check Fuses. Especailly Fuse F2.8 in the CJB. Not a bad idea to check all fuses in the BJB and CJB.

Confirm the operating mode of the PCM (open/closed loop). Datalog the MAF, fuel pressure, IAT, RPM, TPS, ECT, load, LTFT, and anything else that sounds good. Raise and lower RPM's a few times. Post up.

Any changes to the MAFia switch settings?

 

[TurboLs1]

Thanks for the reply, Im not sure what you mean by CJB and BJB, but I checked the fuse box underhood next to the battery and the one under the steering wheel, no fuses were blown. I dont have any means of datalogging, so im limited to basic diagnosis unless I trailer the car to a shop and pay a tuner to check the PCM mode and tune.

By the way, I failed to previously mention that I disconnected the battery for the 3 weeks I was doing the trans swap. I have disconnected the battery before without any negative effects, so im not sure how relevant that is.

I started the car a few times today to really note what it was doing. It starts right up and idles for about 5 seconds, then revs up slightly to about 1300rpm, and then just shuts right off. Right as the car is revving up, I can smell the exhaust and the car is getting extremely rich. If I rev the engine to keep it running, it really wants to die but starts missing and just starts smoking black smoke like crazy...I dont know if its getting this rich because its missing, or if its missing because its just dumping fuel to it? Would it be possible that the PCM has reverted back to the factory tune, or maybe changed modes due to a bad connection in one of the O2's I had to unplug and plug back in during the trans swap? Would checking the O2 connections and reseting the PCM be worth a try? Thanks again for any suggestions.

 

[wmburns]

As your tune is far from stock, I don't know how it will be possible to answer your questions without an ODB2 scanner or datalogger.

So if asking for a WAG, the PCM reverting back to stock is as good as any.

Can't really provide anymore help without access to ODB2 data.

Good luck.

OBTW; BJB=Battery Junction Box (engine bay). CJB=Central Juncton Box (driver's kick panel).

 

[TurboLs1]

Thanks for the reply. Yesterday, the car seemed to run a little better so I tried to drive it up to the local Advance Auto. About a mile from the house, the car died. It started right back up, ran good for about 3 seconds and just died again. It continued to do this as I kept starting it and accelerating as much as possible before it would die again on my way back home. Giving the car more throttle when it attempted to die would only result in the locomotive effect...pumping black smoke out of the exhaust. Moral of the story is, the car runs worse when it gets warmed up.

Today I had a friend stop by my house with an OBDII scanner. I didnt know much about what I was looking at, but the only code we got was a "P1445 Enhanced DTC" code. If im correct, this code points to an AIR error, which I dont think the AIR system is even installed on the car anymore.

Im no ECU expert, but some things I noticed was that the TPS was at 19.6% without touching the pedal and engine off. If the pedal was pushed to the floor, it would only go up to 92.6%, is this normal?

With the engine off, the O2 sensors were reading Bank1 #1 12.55% & 0.160 volts. Bank2 #1 was 100% & 1.275 volts. Bank 1 and 2 #2 sensors were 0 across the board as they are removed. Bank 2 #1 seemed like it is incorrect? My Autometer O2 fuel mixture gauge is also pegged at full rich even with engine off.

My friend also told me that he pulled the "freeze" data from the ECU and that the rpm was at 1357 with the engine off? Not sure what this even means?

From the data above, it looks to me like I may have an O2 sensor failure. Any other ideas? Thanks again for the help everyone.

 

[wmburns]

The TPS percentage quoted are completely reasonable.

The long term fuel trim limit is 25 percent. Therefore, the most amout of adjustment can be made by the O2 sensors is +/- 25 percent. Is 25 percent enough fuel to match your symptom? I have doubts.

Further, there are no O2 related DTCs that would normally be expected in cases of O2 failure.

Besides, did it run OK before the work was done? But having known good O2 sensors to work with can't be bad.

What size fuel injectors are being used? What has been done to confirm that the PCM has not revertied back to the stock tune? Clearly if the PCM is set up for #19's and the actual injector is much larger then a chronic rich condition will result. Likely it will be so rich that the 25% LTFT limit can not adjust.

If you are positive that the PCM's tune is correct for the fuel injectors being used, then use the ODB2 sanner to get the PCM mode (open/closed loop), MAF flow at idle, LTFT, and Fuel pressure. If the MAF output is way off, this could easily cause the symptom.

For this sort of work, the actual voltages of the O2 sensors is not very helpful. Better to look at LTFT's. Compare bank to bank looking for extream differences (left to right/idle to load).

 

[TurboLs1]

Thanks for the response again. The car was running great before doing the trans swap. It currently has 42# injectors but needs bigger so I can up the boost. I think I may just buy some 60# injectors and let a tuner retune the car and fix anything else they may find that is causing this problem. Once I get the problem identified, I will post up the solution for future reference. Thanks again.

 

[TurboLs1]

Finally figured it out, after driving the car and pulling on all the intake pipes, the problem appeared. One of my intake pipes that is plumbed through the fender had worked its way loose. It was still lined up but would spread apart with throttle and or pulling on the pipes. I reconnected the intake pipes and the car runs great again.

On a side note, I bought some new Ford Racing 80# injectors, a Kenne Bell 20v Boost-A-Pump, new fuel filter, and new O2's. Im at 490rwhp now, but aiming for ~650rwhp, getting a new dyno tune this week.

Thanks again for all the help and suggestions!