Hi guys, I know there are some threads similar to this but have not found exact situation as we are dealing with. Here are the details. Overhauled a 2.3 NA in an 89 mustang. Head was redone and new rings. Performed a T5 swap for the factory Auto tranny. Even tho it seems everyone thinks a factory 89 2.3 should have MAF, its seems clear from looking at this car that it is a speed density, not a MAF. Car runs and idles pretty well at startup .
First issue: It is running extremely rich and there is a noticeable hesitation the first several time you hit the accelerator. By the 4th or 5 consecutive time the engine responds better to the accelerator. Did not take long to carbon foul the plugs and it regularly puts black soot out of the exhaust. Seems to use fuel excessively. Strong fuel smell at the exhaust and after shutting car off. Check engine light is on.
2nd issue: Engine idled at 1350 until warm, then increases sometimes as high as 1500. When driving and coming to a stop with clutch in, idle is 1800-2000, then eventually drops back to 1600-1700. Manual idle adjustment screw is all the way in.
Timing advance is set to 11-12 BTDC with spout removed.
Here's a summary of what has been done:
1. IAC reset and TPS check. .92 volts at idle. Also tried blocking off the IAC. Car still ran with IAC blocked but not well. Currently unplugging the IAC does not change idle speed.
2. Compression check-just for fun: 1-174, 2-163, 3-178, 4-179.
3.A friend tried to get codes off the controller: There was a MAP code and PIP (ignition code?). Controller would not let him clear the codes for some reason.
4. Looked for a vacuum leak but did not find one. Tried both propane and carb cleaner. Have not tried smoke machine. Have pulled off all the vacuum hoses one at at time and blocked with my finger. The only one that brought the engine speed down was the MAP sensor vacuum line but also made engine run each richer. Replaced MAP sensor--No change to richness or idle speed.
5. Found that the spring which brings the throttle back to home was weak. Put a stronger spring on--this did bring normal idle speed down to about 1200 but did not change the hanging idle when driving.
6. Checked fuel pressure: 40psi at KOEO. 34 psi at idle, jumps to near 40 psi when throttled. Thought I might have smelled a little fuel smell in the vacuum line to the regulator but it was dry-not wet.
7. Turned key on, then pressed accelerator all the way down to WOT and tried to start. It did start and engine speed took off of course. (I had read to try this to test injector leakage?).
8. While trying some different things, tried unhooking the 02 sensor. Hesitation in the acceleration went away immediately. Have not tried driving it yet to see if this holds true long term or really affects how rich it is running but definitely affected acceleration.
I'm really struggling on the next steps?
--Is the 02 sensor bad? Would this cause it to run rich?
--Does what I did with starting at WOT proved injectors are bad? If not, any other ideas / tests for why it is running so rich?
--Other Ideas on the idle speed not going below 1200? Also on the hanging idle?
--We did not change out the EEC when switching the tranny because I could not find a harness for the manual computer. I was told if we did not have that it was better to leave the auto computer in the car. Is it possible this is the cause of the hanging idle or high idle situation?
Thanks everyone. I know there is a lot of info in there but I could sure use some ideas!
First issue: It is running extremely rich and there is a noticeable hesitation the first several time you hit the accelerator. By the 4th or 5 consecutive time the engine responds better to the accelerator. Did not take long to carbon foul the plugs and it regularly puts black soot out of the exhaust. Seems to use fuel excessively. Strong fuel smell at the exhaust and after shutting car off. Check engine light is on.
2nd issue: Engine idled at 1350 until warm, then increases sometimes as high as 1500. When driving and coming to a stop with clutch in, idle is 1800-2000, then eventually drops back to 1600-1700. Manual idle adjustment screw is all the way in.
Timing advance is set to 11-12 BTDC with spout removed.
Here's a summary of what has been done:
1. IAC reset and TPS check. .92 volts at idle. Also tried blocking off the IAC. Car still ran with IAC blocked but not well. Currently unplugging the IAC does not change idle speed.
2. Compression check-just for fun: 1-174, 2-163, 3-178, 4-179.
3.A friend tried to get codes off the controller: There was a MAP code and PIP (ignition code?). Controller would not let him clear the codes for some reason.
4. Looked for a vacuum leak but did not find one. Tried both propane and carb cleaner. Have not tried smoke machine. Have pulled off all the vacuum hoses one at at time and blocked with my finger. The only one that brought the engine speed down was the MAP sensor vacuum line but also made engine run each richer. Replaced MAP sensor--No change to richness or idle speed.
5. Found that the spring which brings the throttle back to home was weak. Put a stronger spring on--this did bring normal idle speed down to about 1200 but did not change the hanging idle when driving.
6. Checked fuel pressure: 40psi at KOEO. 34 psi at idle, jumps to near 40 psi when throttled. Thought I might have smelled a little fuel smell in the vacuum line to the regulator but it was dry-not wet.
7. Turned key on, then pressed accelerator all the way down to WOT and tried to start. It did start and engine speed took off of course. (I had read to try this to test injector leakage?).
8. While trying some different things, tried unhooking the 02 sensor. Hesitation in the acceleration went away immediately. Have not tried driving it yet to see if this holds true long term or really affects how rich it is running but definitely affected acceleration.
I'm really struggling on the next steps?
--Is the 02 sensor bad? Would this cause it to run rich?
--Does what I did with starting at WOT proved injectors are bad? If not, any other ideas / tests for why it is running so rich?
--Other Ideas on the idle speed not going below 1200? Also on the hanging idle?
--We did not change out the EEC when switching the tranny because I could not find a harness for the manual computer. I was told if we did not have that it was better to leave the auto computer in the car. Is it possible this is the cause of the hanging idle or high idle situation?
Thanks everyone. I know there is a lot of info in there but I could sure use some ideas!
