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Miss like it hits a brick wall at 4000 RPM


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Posted

Lately, whenever I get on it, right as it hits 4000 rpm's, it's like it's the rev limiter. It will bounce back to about 3500-3600 rpm, and bounce back and forth until I let off. Otherwise, the vehicle drives fine. Idle's fairly smoothly, all gaskets are fine. Wires and plugs are perfect. ICM and Coils are fairly new, but they could be going out. The ICM and Coils are from a 99+ 3400, they were supposedly brand new, off of ebay.

 

Any suggestions, maybe try a new set of coils and icm? Anything else I should check?

 

Also, fuel is fine. Fuel pressure is fine, injectors are cool.

 

BTW, this is also posted over at 60degreev6.com.

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Posted

Check to see if you are actually hitting fuel cut off. You might not be getting the VSS or PRNDL signal somewhere and it might still have the idle cutoff enabled.

Posted
Check to see if you are actually hitting fuel cut off. You might not be getting the VSS or PRNDL signal somewhere and it might still have the idle cutoff enabled.

 

But why such a low RPM?

Posted

Built in from GM to protect aginst any type of "free-spin" damage.

 

Basically to stop some ass-hole from revving his engine in neutral...

Posted

as i recall his cars got bens chip with te rev limiters removed...

Posted

Yea, White, you're right. Says is in his Car Domain site...

 

Hm...good question...

 

Ign. Module Going out than? This one has me really stumped

Posted

Neutral park safety switch is going out. I put it in Neutral, revved clear up to 5k fine, any other gear only wants to rev up to 4k. So, where's this located at? Theres a 93 Z34 being stripped less than a mile from here.

Posted

sits on top of the trans on the drivers side. It will be attached directly to the trans and a plug will be attached. I am pretty sure it is on the very top of the trans on the drivers side

Posted

i almost want to say its something with the ICM/Coils, since it waves just a little at idle. but all said i'm kinda at a loss on this one considering it revs fine in neutral.. it could be a load on the engine thing.

Posted
I think it's a P/N switch out of calibration. Replace that first.

 

Where's that at?

Posted

check for water in the sprak plug holes or a ignition problem of sorts. have you drove the car with teh fuel pressure gauge and watched what it does when you accelerate?

Posted

No water in the spark plug holes, done checked that. I can hook up that guage and check it out while I'm driving, if it will reach.

Posted
I think it's a P/N switch out of calibration. Replace that first.

 

Where's that at?

 

First, I just read my thread again and would like to take back the "calibration" part. I just think it's bad. I'm not sure where it is offhand, sorry. :(

Posted

its just as if you were to take a z34 with the factory rev limiters and mash the gas in park till it bounces off the 3k rev limiter.

Posted
its just as if you were to take a z34 with the factory rev limiters and mash the gas in park till it bounces off the 3k rev limiter.

 

Exactly what he says. I couldn't describe it any better.

Posted
well what did the fuel pressure do when you drove it?

 

Well, attempted to hook it up, but the guage doesn't want to reach far enough to be able to see what its reading with the hood closed. In park, it sets a little under 40.

Posted

Ended up taking out the hood vent and propping it up out of that. At idle, sits right around 38, driving is about 40-ish, at 4000 rpm, it is right about 45 (this guage is kinda crappy, but it works). When it bounces back and forth, it bounces from 42-45.

Posted

ya thats what i expected, i would start swapping some ignition stuff, or start ohming out teh wires and coils

Posted

I pulled the plugs off of each coil pack, and put my tester up to them. They seem to all have fine resistance. How do I go about checking the wires?

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