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no power at full throttle

10-23-2004, 06:09 PM
I hope someone can help. My 1990 3.1 engine Z24 runs great at idle and half throttle, but as soon as I put the pedal to the floor the car looses all power. It is like there is a rev limiter on it. It will increase RPM but very, very slowly. But as soon as I let the pedal up to half throttle the car takes off and is fine. I did a fuel pressure check, and hooked it up to the computer and everything is good. I have changed plugs, wires, TPS, and even the ECU. Nothing has helped. Now today I was driving and put it to the floor and it went like a bat out of hell, so I tried it again and it was back to falling all over itself again. Please help I am really lost on this one.

10-24-2004, 01:17 AM
Thats really wierd. Might want to take it to a shop and have them check all the internals.

10-24-2004, 01:18 PM
unboltyour exhaust before the convertor could hav a plugged up convertor.

10-24-2004, 01:52 PM
There is now a new twist to the problem. The car runs great the first time you drive it in the morning. But after the car is ran for a short distance it starts to do the same thing. I have now also checked the MAP sensor and the IAC. I guess my next step is to check the converter. If the converter is plugged would the problem come and go like it does? Thanks for all the help.

10-25-2004, 02:25 PM
Yes, once it warms up it will constrict and block up.

Check that first at a shop and have them do a back pressure test.

10-25-2004, 06:59 PM
sounds like cat. converter to me too. sometimes if they get really stopped up they will turn orange(glowing) and you can see it really well at night time

10-25-2004, 09:10 PM
The exhaust seems to be flowing fine and the cat does not get any hotter than the rest of the exhaust. It sure does not get hot enough to glow.
But I guess I will take it in to get the cat checked out.

10-25-2004, 10:36 PM
If it is not that, we will move onto getting the codes scanned.

10-26-2004, 08:11 PM
I have now changed the O2 sensor and the Knock sensor. Now if you ease into the throttle (less than Half way to WOT) until you get it to 3500 RPM then put it to WOT the car runs great. But if you try to put WOT after the car is warm from any RPM less than 3500 it falls all over itself.

10-26-2004, 08:16 PM
Have you had the codes scanned?

10-26-2004, 08:30 PM
ya put it in park or nuetral, if your engine hits 4 grand and acts like its on a rev limiter, its the nuetral safety switch, these cars from what i understand is that they have a rev limiter in park or neutral for some reason, and when the switch goes bad it thinks its in park or neutral, it doesnt affect if it starts in P or N but it does that.,

My car was stumbling also, and i put a new one of those switches in, car runs like a top, try that.. also if nothing else works,

just a thought

10-26-2004, 08:50 PM
There are no codes an I had it hooked to a scanner and it said everything was good. I am just shooting in the dark now trying different things but it is starting to cost to much to keep doing that.

As for the nuetral safety switch? If the car revs over 4000 RPM in N or P. Does this mean the switch is bad? When yours did this could you get your car over 4000 RPM, because I can get it to red line but I can not put my foot into it until I am at 3500 RPM or it falls all over itself?

10-26-2004, 08:57 PM
Sounds like the fuel pressure regulator might need some looking into.

Have you ever changed the fuel filter?

10-26-2004, 08:58 PM
Changed fuel filter and did a fuel pressure test. Everything was good.

10-26-2004, 09:03 PM
I would still go and have the exhaust back pressure tested.

Also, pressure testing in park does not say everything is fine when you are accelerating. You need to see if there is any pressure drops when you are accelerating.

10-26-2004, 09:06 PM
We did a driving fuel pressure check also. The pressue went up when we went to WOT.

10-26-2004, 09:09 PM
Also someone told me that it maybe the CPS or the ICM, does that sound like it could be those things?

10-26-2004, 10:06 PM
can you redline it in p and n?? im all kinds of confused with my frinkin car, if its not fuel? then i would also look into the exhaust.. Could there be a bad vacumn line somewhere?? hear any hissing coming from the motor??

Thats what i told about my 97 z24 2.4 now if this is true or not i dont know but this is it. no more money into that car.. Next take it to the dealer and see what he can do with it.

10-27-2004, 06:28 PM
Yes I can red line the car in P and N. Checked all vacuum lines and even replaced some just because they looked old but still no good.
I guess this weekend I am going to pull the coils and ICM and check them out. I am sick of this POS!!!

10-27-2004, 07:24 PM
ignition coil pack(s)!!

10-30-2004, 12:58 PM
Thank you everone that help me. I changed the ICM (which was cracked) and the coils (which one was cracked). Now it runs great.

10-30-2004, 08:40 PM
Glad To Hear You Got Your Car Running Right Again!!!!!!!!!!!!!

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