Thread: Idle went whacko....please point me in the correct direction.

I would *assume* that I should start with this thread from our How To section and follow the steps?

http://www.sr20-forum.com/general-maintenance/38-how-bad-idle-troubleshooting.html

Here is what is going on, please point me in the right direction.


Ran a few errands. Ten miles, about four stops total.

The car was running great at first. Driving it quickly as usual.

The car died at idle at the first stop sign.

After that, the car idle would not stay consistent.

It was steadily jumping/surging between 400 and 1100 rpms.

The car would eventually die after surging for maybe a minute or so. It would finally drop below about 3-400 RPMS and simply die. I could keep it running if I kept my toe in it and kept the RPM's around 2-2500 RPM's.

Heading home it was hesitating and sort of bucking under load. I kept the RPM's down, and it cruised OK.

Made it home. Kept the RPM's up with my toe while going down my driveway. Parked it in my garage.

Re-started it. Same idle surge 400-1100, up and down pretty steady. A minute or two and it would die. Once again, I could keep it running if I kept my toe in it and kept the RPM's around 2-2500 RPM's.

I checked every single connector, fuel injector, electrical lines, spark plug wires, and hoses. Nothing *seems* amiss visually/by hand. No loose wires to the battery or alternator. Spark plug boots are tight.

I have one (1) small vacuum line that needs to be replaced. Here's a pic of said vacuum hose.



That location/device is just to the right of the fuel filter and below the tank for the brake fluid. That little thin vacuum line on top is bad. I dunno what it is, or if it affects the idle. I can replace it easily enough, and will.





With the information provided, do I use the How To posted above and follow it as directed?

Thank you for any insight and direction. Keep in mind on any "direction" my incredibly low-level of mechanical expertise.

Shawn B

I know you said you checked everything but did you make sure that the MAF is fully connected ?

Had the same thing happen to me and sure enough it was the maf, make sure it's snapped in

First thing, take care of that vacuum hose. It comes from the intake manifold and goes through a solenoid or two before eventually ending up at the actuator for the charcoal canister (which is what you've got in your picture there). A vacuum leak can cause the idle to overshoot and then bog. For a temporary test, you can block off that line with some vise grip pliers before the hole. If that fixes things, then you've found your issue.

Then follow the steps in the thread you found, or look up the procedure in the FSM?

My guess is MAF or TPS. Have you performed a MAF reground in the past?

If it also had trouble driving ... id say the spark plug wires

Sounds like MAF to me. Also reset ECU, that has worked for me a few times when sh!t went goofy.

I'm going with a blocked EGR or the IACV needs cleaning or replacement if it isn't the vac line.

Thank you gentlemen.

You folks mentioning MAF reminded me of something.

Maybe 5-years ago I had eerily similar symptoms. Took the vehicle to Mike my mechanic (gawd-dammit I miss that dude) and he had to replace the harness-side connector that went to the MAF. We got a connector/pig-tail from Andreas as the only other way to source that connector is to buy an entire new wiring harness. Mike spliced it in and all has been well.

I bet it's the damn MAF. I will be checking it within the next hour or two.

Thanks for the help and suggestions so far. I don't know why I did not think of the MAF already.

Shawn B

You do have the MAF grounded to the inector harness ground on the intake manifold right?

I do not know. I know that Mike checked the MAF ground when we did the connector swap. He made sure everything was A-OK.

As I am now at least attempting all my own fixes, I will be checking the ground when I check that previous connector-splice-fix.

I will be heading out to my shed/garage shortly and will see what I find. I'll take pics of anything I don't understand or that looks sketchy.