Engine back together but now surging

mrclean302 · Jul 17, 2007

I already know about the link on how to fix surging, but I have a couple questions to
ask first.

I put new heads and intake on and after about 45 seconds of cranking, it started up.
Kind of.

It would surge from approximately 500rpm to 1500rpm, probably higher. I was shocked
the car started up, this was the first time I've every done this type of work.
Anyway, it only ran for about 3 minutes and died on its own. I didn't try starting it
again because I have a little interference problem with two spark plug boots resting
on the header and didn't want to burn them. GT40P heads with FMS Headers.

So if anyone has a shorty spark plug part number for GT40P heads let me know.

Kind of rambling here but here is the real question. I want to know if the car had run for say
10 minutes or longer, would the computer have had time to adjust itself to the new
combination and run good enough to drive? Or should I just go through those steps now?

Thanks in advance.
George

quickstang_1994 · Jul 17, 2007

start checking for vaccum leaks

mrclean302 · Jul 18, 2007

So this definitely sounds like a vacuum leak? I'm 100% I hooked all lines up.

What is the best way about finding this?

ripper · Jul 18, 2007

It will take more than 10 mins for the puter to adjust. Might take 100 miles, might take 50 miles. You never know. Mine took like 200 miles. Dont beat it for a while. Let the puter adjust.

Anrev · Jul 18, 2007

Ok so you got all the vacuum lines hooked up. But are you sure they arnt leaking? And are you sure the upper and lower intakes are sealing properly? Get a couple cans of WD40 or carb cleaner and spray down everything and listen for the engine to rev up. Make note of where you were spraying at the time and you'll have located a vacuum leak. Pay attention to the mounting surfaces of the intake where it meets the heads. If you spray along those and you get a surge then you will have to take the intake back off and try reseating the gasket. And make sure you use proper torque sequence and steps.

mrclean302 · Jul 20, 2007

Turns out one of the plugs I was having trouble with wasn't connected properly. Corrected that and fired her up for a couple
of minutes. Surging was almost completely gone going up and down maybe a couple hundred rpm until it stalled out again.

Started it again and it died almost immediately. Tried again and died again. Third time I started it and gave it a little gas
and she ran perfectly with my foot on the throttle. As soon as I let go it stalls out.

Any ideas?

quickstang_1994 · Jul 20, 2007

tap on the IAC valve.

Anrev · Jul 20, 2007

Big vacuum leak. Same thing happened to mine. You probably have a leak at the intake manifold.

ryclef331 · Jul 20, 2007

read the surging article again....specifically the part about setting the idle. Your new mods are allowing for more airflow even at idle. The IAC and throttle body aren't letting that through sufficiently...so you have to adjust. There is an idle screw on the TB (not the one that the linkage rests on). Its on the top (if your car is stock its covered with a little rubber plug). Back that screw out to raise the idle. You CAN use the linkage stop screw but it will also increase your TPS voltage so it will think you're ON the gas when you're actually not causing a slightly richer idle....no biggie really but it still isn't "right."

I don't think you have a vaccum leak...just need some tuning.

mrclean302 · Jul 20, 2007

Ok. I'm gonna go through the article again and see what I can do.

If it was a vacuum leak then wouldn't it still run funny when I raised the rpm?
It was dead solid when I was holding it at 2000rpm.