Very strange engine behavior...Help! MAP Failure?

I was idling at a light today when i noticed my idle started jumping around a bit , and then evetually started jumping between 1500rpms and dropping down low enough to almost dying , I headed straight home , and the symptoms only got worse , the car would go between dying out and slamming me into my seat under any application of throttle...I'm thinking seeing as how its been raining profusely for days now , it could be a waterlogged sensor somewhere causing this erroneous behavior. Any other ideas? There was no SES code or any signs of this happening before this.

have you gone over all the vac lines? i know most of them were held together with tape.

Not most of them....just one of them....

But good call... I'll check it out.

Checked the vacuum lines , and they are fine. Started the engine up , and it ran perfect. Didn't take it for a drive , but I'm thinking i might have just ran over a puddle and soaked a sensor , and I don't think its engine related. Maybe a trans lockup issue? I had similar but not quite identical symptoms on my last car , but it wouldn't explain why it revved up like that.

Just took it for a drive , even redlined it , car seems to be running just fine.


Wet weather does some strange things to electrical systems.

Quote :

Maybe a trans lockup issue?

That was my first guess, but if the TCC is not disengaging, the SES should come on after 2-3 trips. I hope this is not the case.

Yeah well i think on my day off I'm doing a trans fluid and filter change just to be safe. And i'll be taking it easy on it for a while.

so, no valve float at redline with the mod'd 1.9's?

glad to hear it was a fluke, and hope it doesnt come back.

None that i can tell. At first i figured it was an issue with the 1.9s and that i bent a pushrod or something , but knock on wood its been fine all day.

How old are ignition wires?

FWI grab some water maybe? If the MAF got wet... all kinds of crazy...

deekster_caddy wrote:

FWI grab some water maybe? If the MAF got wet... all kinds of crazy...

Quite possible. I did drive through some kinda deep puddles not too long before that. I've been careful driving all day though.

H2O injection FTL

AA wrote:

How old are ignition wires?

They have just under 15k miles on them.

Let it get to dusk when it's slightly dark out. Start the engine and lightly mist each sensor one by one.

Something is going on.. you don't want to have an issue on the road again.

Recently I had a TPS fail on me. It was hanging between 3 and 10% according to the aeroforce. Kinda sucks when you are holding back 10% with undersized brakes on a 400+hp motor. A couple taps to it cleared it's issue, it worked great for the next 2-3 days until I swapped it out.

Be willing to have a helper tap and wiggle while you watch TPS and other sensors.

DId some scanning today , and sure enough after a while it came back. However i noticed that my boost reading was a steady 0.29 , so it could very well be that my MAP sensor has failed. Would this cause this sort of problem? Either way I'm gonna replace it.

On a bright note , Between the 99+ MAF tables now and rockers I only have a few blips of KR midway through 2nd gear and other than that none up to 100. ( I did this before i noticed the MAP sensor was messed up)


Also I ruled out the possibility of it being trans related since it did the same thing when it wasn't in gear.

Update again...turns out we didn't hook the vacuum line back up to the MAP sensor after installing rockers. I think this should solve the problem.