what would cause the car to idle fine but not rev?

[project03r/t]

It's been some time since I have been able to tinker with the car again, but I'm back at it. It starts no problem, and idles with zero issues, but the only way I can rev the car is to go very lightly and slowly up the RPM range. Even then if I let off the gas all at once it just shuts down. And if I rev the car quick it just dies immediately. Any suggestions? TPS wiring problem, vaccum problem...ground problem? Any people have any experience with this issue?

[rija]

It's been some time since I have been able to tinker with the car again, but I'm back at it. It starts no problem, and idles with zero issues, but the only way I can rev the car is to go very lightly and slowly up the RPM range. Even then if I let off the gas all at once it just shuts down. And if I rev the car quick it just dies immediately. Any suggestions? TPS wiring problem, vaccum problem...ground problem? Any people have any experience with this issue?

Check your fuel pump

[project03r/t]

The fuel pump comes on no problem when the car ignition is turned to on. The Walbro is pretty noticeable and my fuel pressure gauge is reading good fuel pressure at the rail. I was thinking that since I have the MAP clamped using voltage mode but currently set to zero across the board, it might be messing up the ECU?

[Elevationtc]

The fuel pump comes on no problem when the car ignition is turned to on. The Walbro is pretty noticeable and my fuel pressure gauge is reading good fuel pressure at the rail. I was thinking that since I have the MAP clamped using voltage mode but currently set to zero across the board, it might be messing up the ECU?

change voltage to percent on maf.. done

[Raj]

Yea that could be it.  Try changing to percent if your going to keep the table at zero. 

[project03r/t]

Hey Raj, thanks for chiming in. And thanks Elevationtc for the suggestion. unfortunately that's the not problem (although your logic is sound and I did change it to percent so that I wasn't sending a "0" value to the ECU). I pulled the newest batch of codes and here is what we have:
p0508   IAC control valve sense circuit low (low voltage)
p0688   ASD Sense Circuit low
p0107   Map sensor low voltage
p0135   02 1/1 heater performance
p0038   02 1/2 heater circuit high

My money is on the ASD voltage being low. That could cause the car to lose fuel and spark and cut off after reving the motor. It only happens if I let off abruptly or hit the gas abruptly. If I gradually get on the gas then gradually get off it, the car will remain running. If I do it fast, it dies immediately. I notice super fast leaning out on the wideband.
Is my logic sound? I'm thinking maybe a ground/fried relay/loose relay?
If that makes sense I'll check it out in the morning.

[Raj]

Voltage for the o2 heaters and alot of other devices such as injectors does come off the asd relay so yes you could check the asd relay input/output for proper battery voltage when this does happen.  But I would also check the map voltage code too since it doesn't share any wiring with the asd relay.  The easiest thing to do for the map code is to just bypass the map in/out to the fic and see what happens.

[hive]

I had similar problems and it turned out to be wwong Injector response time. Changed from 485 to 2075 and it was a bit better but still had problems. After several trial and error changes finally found out that 1875 us works like a charm

[project03r/t]

Raj, when you say bypass the map wires, you mean go back into the wiring harness and yank the F/IC wires out? i tapped into all of my wiring about a foot from the actuall connections into the ECU.
Hive, I hadn't thought of the injector timing....perhaps I'll give that a shot

[Raj]

Basically put the map wires back to stock.  You can try adjusting the inj. response.  I didn't have luck with that when I was trying to get back my throttle response.

[project03r/t]

adjusting the injector response time definitely had a positive impact on the car. I was able to rev and let off the throttle. The car would hiccup when dropping back to the bottom (~850 rpm) but wouldn't stall. and no more hiccuping on the way up the throttle. I was able to drive the car from one house to the other with no threat of stalling. I did keep the car out of boost for the most part and no WOT. I need to figure out a good map for the MAP. Do you have a good clamp voltage or percentage map that I could base mine off of Raj?

[hive]

It seems to me that you still have to play with injector response timing. I have spent around two weeks on finding the correct number and it always turned out that some umber which was ok for somebody else wasn't ok for me lathough it was used on same injector type. Keep playing with it. If you get hick-ups while driving try to put in smaller numbers (lets say lower it for 100) if it gets better lower further until you get a good IRT. If going lower does not help than add some. I have read of people using up to 2600 as their IRT 

[project03r/t]

thanks Hive, I'll keep working on it. I Think Raj is right about the MAP wiring. I'm going to see how I wired it and put it back to stock to see if that changes anything. If it does, then I must have wired it wrong. Ugh...wiring can become a major enigma really easily.

[project03r/t]

I have the MAP wiring as such: Intercepted (cut the Map wire at ECU [can't remember C2 pin number] and placed MAF in on the harness side,and MAF out to the ECU side) and I want to make sure that is how everyone has theirs set up. The wiring diagram listed for the Dodge neon/srt-4 is what I used to determine how to hook everything up. The only thing I changed was the 02 sensor wiring. The diagram shows the O2+ going before the 1K resistor, and I put it after the resistor but before ECU. Is the fact I intercepted the MAP wire instead of tapping it making the car run so strange with the snap throttle from idle?

[Raj]

You have it intercepted correctly.  Buy for giggles, try eliminating the fic from the map circuit and see what happens. 

It was a long time ago since I had some issues but I think that was one of the issues I originally had.  I'm pretty sure thats why I added the diodes to the injector circuit.  Post up you cal file.  I'll try to get mine up this weekend, maybe it'll work better.