start, run, power all need u

[wotpoc]

Well, I've been trying very hard for 3 years to solve some problems on my 88 GT, reading hundreds of posts, trying dozens of things, spending money, still no solutions.

Here's what I've got, then I'll try to describe my woes quickly...

88 GT, AFR 165 heads, 1.5L Kenne Bell blower with 9psi pulley, 24 lbd ford motorsport injectors with 93 cobra ECM (new from ford motorsport), mass air conversion, new: TFI, cap, rotor, wires, plugs, ACT, ECT, coil, TPS (0.995V at closed throttle), IAB, 255lph pump, fuel regulator, fuel filter, insulation wrap on headers, located ACT in cold air intake tube

Probs:
1. Cold start - starts, but dies, will then start and idle after a couple tries, but give it gas and it will nearly stall. After 2 minutes, all is well! Very difficult to drive first 2 minutes.

2. Hot start - run it till fully warmed up, let it sit for 15 minutes, then it will start and imediately die. Repeat oever and over, it won't keep running but will monentariy run each time I try to start it. If I give it gas I can keep it running, but it's rough. I rev it for a while and it clears up and will then run fine. Vapor lock? If I let car sit with hood open after running this will not occur.

note: This hot start prob did not exist before mass air conversion and cobra ECM, and 255 lph pump were installed, but blower was installed.

3. run up the rmp on accleration, let off, then it idles high, anywhere from 2-3K rpm. If I snap he throttle fast and hard it will come back down. I disconnected cruise control cable to elliminate that possibility. No difference. I can shut engine off while it idles fast, restart in 2 seconds, and idle speed is normal! So two things can return idle to normal: 1, snap throttle, or shut off engine and restart it right away. Mechanically I can find no bind or trouble, the throttle butterfly returns to the stop just fine, doesn't appear to be slightly stuck open. Seems like computer gets confused..?

4. After warmed up, loss of power at rpm above 3-4K. It feels like it cuts out power, then back in to power, then out, so it jerks several times per second when pulling hard. This does not happen with ACT in intake manifold connected to ACT harness, it just has low power all the time after warm up. I move the harness to the ACT in intake tube and the power is great, until fully warmed up and higher rpm then it quickly cuts in and out. When cold it pulls really hard past redline. Definitely seems engine temp related and it seems the ECM gets confused and cuts power back. IT is a very noticable difference.

I can live with probs#1 and #2 if I have to, but not with #3 and #4.

Error codes:81, 82, 95. Interesting, all Thermactor stuff. I think the '93 cobra ECM is not compatible with the wiring to the solenoids for the thermactor circuits in my '88. Anyone know? would this cause any driveability probs? I thought it would only effect emmissions. But maybe my hot start prob is rooted here?

I really need some help, I'm spinning my wheels. Thanks!!

 

[Mike92GT]

Which mass air meter are you using?

 

[vristang]

Did you use a 93 Cobra MAS (sensor)?
Or the A9L sensor that probably came with the MAF conversion kit?
Or was the Cobra EEC in the MAF conversion kit?

The MAS for the A9L and X3Z computer are different. They will output different voltages for the same airflow, in the same tubes. Depending on your setup this could barely be noticeable, or it could be really bad.

I wrote a FAQ a few days ago when I found out this was the source of some of my tweecer tuning issues.
http://www.freewebs.com/vristang/faqs.htm

I can't say for sure that this is your issue, but it is something to look into.

Good Luck
jason

 

[Roland69]

should've registerd sooner and welcome to SN sounds like you have a nice setup minus the current problem.

 

[vristang]

3. run up the rmp on accleration, let off, then it idles high, anywhere from 2-3K rpm. If I snap he throttle fast and hard it will come back down. I disconnected cruise control cable to elliminate that possibility. No difference. I can shut engine off while it idles fast, restart in 2 seconds, and idle speed is normal! So two things can return idle to normal: 1, snap throttle, or shut off engine and restart it right away. Mechanically I can find no bind or trouble, the throttle butterfly returns to the stop just fine, doesn't appear to be slightly stuck open. Seems like computer gets confused..?

4. After warmed up, loss of power at rpm above 3-4K. It feels like it cuts out power, then back in to power, then out, so it jerks several times per second when pulling hard. This does not happen with ACT in intake manifold connected to ACT harness, it just has low power all the time after warm up. I move the harness to the ACT in intake tube and the power is great, until fully warmed up and higher rpm then it quickly cuts in and out. When cold it pulls really hard past redline. Definitely seems engine temp related and it seems the ECM gets confused and cuts power back. IT is a very noticable difference.
!!

Sorry, I guess I didn't read the whole thing.

3. I have had this problem before and it turned out that there was a little corrosion in the throttle cable guide. I ended up packing the cable guide with grease and the problem went away forever, well it's been 8yrs. I never did see the throttle plate stick when I inspected it.
If that does not work then check out the Surging Idle Checklist by jrichker. It should help for this problem.

4. Is there a reason why you mounted the ACT in the intake tube?
The Fox mustang computers were setup for the heat range that would be seen if the ACT were mounted in the lower intake. By putting the sensor in a other than stock location the calibration for that sensor becomes worthless.
You will also have some issues with the added heat from the KB blower. The high reading on the ACT will cause the EEC to freak out, as you have found out.


I think you can get this setup running pretty well as is with a little more trouble shooting, but you may be getting close to needing a tune. That is just my opinion though.

Good Luck
jason

 

[wotpoc]

Thanks for your suggestion on the throttle cable and packing it with grease. I'll try that.

I mounted the ACT in the intake tube because Kenne Bell recommended that in SD cars as to not lean-out too much. But then I converted to MA, so maybe it's a bad idea to put in in the intake tube? I just get so much more power (very noticable difference) when it's in the intake tube...

I will check whcih mass air meter I've got. If I recall correctly it came with the MAF conversion....

The Cobra EEC came separately from the conversion kit I recall.

I'll check out the link you suggest. Thanks!

 

[wotpoc]

When I looked tonight at the throttle cable for bindinf, I noticed the butterfly in the throttl was sticking! IT turns out the problem was the butterfly was slightlt loose on the shaft, so sometimes it would bind when closed, getting sticky, and sometimes it would shift a little and prevent it from closing completely, hence the high idle speed sometimes. I tightened the allen screws down well, adjusted the idle stop, and all is well with that!

I think my MAS is for X3Z, F1SF-12B579-AA AFH70-02 1E15. I believe the "70" means 70mm. I've noticed a "55" in this part of the number for 9AL equiped cars.

One prblem down, a few to go. Thanks for your help so far!