Delayed maintenance….

[grendiers]

My ‘89 car has 79,000 miles on it, up from 65,000 miles over 8.5 years of ownership. Since day one, I have had an occasional surge at idle when cold. At some point, I replaced all of the vacuum hoses with silicone. Didn’t solve the problem. Now, it’s pretty much all of the time when I first start it.

When warm it never does this. The car is running rich by the looks of the tail pipe. It pukes black spit, but not always. I can clear the surging by driving just a bit. When you pop the hood, you can hear air sucking noise, which is coming from the idle control valve.

The car is chipped in both the DME, and the KLR. No vacuum leaks that I notice. Idles at 900 or so when warm. I have a spare KLR without a chip I could install to see if it clears the problem. If the KLR is the problem of course.

Lastly, the engine blows a bit of blue smoke out the back for a few seconds when cold. The head was rebuilt in 2005 at 62,000 miles according to the service records I have.

And another thing, the front mounted oil cooler leaks a bit of oil, and coolant over the winter months in storage. Not when I drive in the summer. Thanks! Dave

On a whim, I replaced the 3 bar FPR with the OEM stock version. No surge in idle this morning nor smoke, idled like new.

[944 Ecology]

I would recommend two tests:

1) a smoke test... tests all of the vacuum hoses for leaks. Smoke is a good visual indicator.

2) a boost test, tests the integrity of the boots and connections under boost (some cracks only open up when the pressure rises.)

[grendiers]

Well, swapped out the KLR, and cold startup, which I thought had cured with the change to the stock FPR, idle still surged up and down. But, i popped the hood and started messing with the hose clamps, and found a loose one attached to the thinner metal pipe. Behind the ICV area. There s a bit of oil though, in the KLR line.

[grendiers]

I’ll have to wait til tomorrow morning to see if it’s fixed. Both computers have ‘chip’ written on them. So, back in the other one goes! Not a fun job!

[kdjones2000]

Dave, I wouldn't run your chipped car (DME, not KLR) with the 2.5 bar FPR, at least on boost. The chip is tuned for the higher pressure, and when you lower the pressure you are leaning out the mixture.

Have you looked at the FQS setting on the DME? Most chips have rich/lean settings, depending on the FQS position. Any idea what chip is in the car?

Really hard to diagnose without know what you are dealing with.

[grendiers]

Hey Keith, good to hear from you! Looking at all of the service records, looks like they are from Lindsey Racing. I have other chips that came with the car, they look like they were never installed. I’m going to reinstall the 3 bar FPR today. Weltmeister and 951Max chips and the stock DME chips are my ‘spares’. I didn’t look at the settings; above my pay grade! Work was done at Beck’s European in Scottsdale.

[kdjones2000]

Keep in mind that your engine is running in open loop mode while it is cold. Only when the O2 sensor has warmed up enough does it go into closed loop mode (using the O2 sensor).

It could be that the engine is running rich/surging while in open loop mode, and cleans up after it transitions to closed loop mode. Have you checked your fuel pressure at the rail? Also, pull the vacuum lines at the Fuel damper and FPR and check for fuel leaking into the vacuum system.

It really could be many things, but that's a place to start.