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What's your oil consumption been like? Have you pulled the side intake plenums and looked at the amount of oil in them?
Do you have one of the after market oil disengaging devices installed under the oil filler neck? Is the check valve in the vapor return line back to the MAF malfunctioning somehow?
Only going down this route wondering if the MAF wire isn't getting oil coated and giving false readings.
Spec for '87-up FPR (for S300s chips) is 55±3 psi (cold 52 < 55 > 58 hot) with vacuum hose disconnected.
That idle vacuum would pull it down about -9psi (2:1 "hg to psi), so it looks OK running?
It should hold at the nominal pressure after shutoff for a while though, so that number is odd.
Need to check with relay jumpered.
Ok, I will verify with relay jumped and probably running w/o vac line as well.
I have a new fuel pump and filter to put on if numbers remain suspect.
Yes, it runs ok, a lot better then I would think for the numbers I see. I’m always amazed how little these engines complain. But it runs better with temp 2 disconnected, which is still freaking me out.
How should i interpret response to temp 2?
Is that a normal response to run richer and higher rpm without sensor?
I cleaned sensor and housing last night but no change. I have new one coming.
Cold start running at idle 48-49 psi with vac line attached to 87 FPR. Will hold pressure at 51.
Cold start running at idle 57 psi with vac line NOT connected to 87 FPR. Will hold pressure at 53. So this sounds like fuel delivery, at least to injectors is ok right?
Fuel pressure sounds right. (I had the cold/hot numbers swapped, corrected above.)
IIRC, the S3 LH doesn't know if the Temp II is disconnected. If no error checking, disconnected = high resistance = cold. (S4-up LH defaults to a warm value on error.)
Did you check each terminal of the Temp II to ground? There are two sensors inside for EZ/LH. Each side should be about even, cold and hot.
The values were about/essentially even both hot and cold.
I can check them at computers to confirm no damage to harness.
Can somebody confirm EZF is pin 23, and LH is pin 2?
I took her out to get more numbers on the road today. The lean condition is really only at idle. Driving with any throttle it will try and get to 14.7. WOT will get down as low as twelves.
I would say good performance, the exception is again at idle, where it can feel like it runs rougher.
I'm not sure this is a new condition, either. I can remember having to turn up last MAF quite a bit to get lower AFR'S (700's) on the last tune several years ago. Maybe the difference recently is that that MAF gave out and with new MAF set at 308 I'm lean again?
I should have new O2 sensor and temp 2 sensor by tomorrow.
Just for those that may search for lean conditions down the road, thread update.
I ended up wiring a narrowband on the o2 sensor side and got a lot of sweeping but not a consistent lean condition. This seemed inconsistent with the wideband on the other side.
I had done some other parts replacing, ignition modules and temp2, with no luck as well. At that point, I resolved to just systematically check everything, and check one box at a time.
I purchased a smoke machine, they are pretty reasonable now, 150-180 will get you a really good unit. I saw a pretty big leak coming from the driver's rear intake gasket area (also wideband side). Surprised because the idle speed was really not affected, but go figure.
As I pulled off the intake, it was apparent that the rear of the gasket had shifted. I assume during my last installation. Nobody to blame but myself.
With new gasket, AFR was dialed in and no further concerns.
Crumpler,
Bookmarked this thread for future reference...lots of good data for 85/86.
Can you post a link to the smoke machine(s) you referenced, and make any suggestions?
I think it is about time to buy one and get down to some serious fine tuning of vacuum issues.
-Jason
Just for those that may search for lean conditions down the road, thread update.
I ended up wiring a narrowband on the o2 sensor side and got a lot of sweeping but not a consistent lean condition. This seemed inconsistent with the wideband on the other side.
I had done some other parts replacing, ignition modules and temp2, with no luck as well. At that point, I resolved to just systematically check everything, and check one box at a time.
I purchased a smoke machine, they are pretty reasonable now, 150-180 will get you a really good unit. I saw a pretty big leak coming from the driver's rear intake gasket area (also wideband side). Surprised because the idle speed was really not affected, but go figure.
As I pulled off the intake, it was apparent that the rear of the gasket had shifted. I assume during my last installation. Nobody to blame but myself.
With new gasket, AFR was dialed in and no further concerns.
Just read through this and I had the exact same issues on my 91 GT SC. Ended up being a pretty good vac leak around the injectors. Sealed them all up and everything went back to normal.
Just for those that may search for lean conditions down the road, thread update.
I ended up wiring a narrowband on the o2 sensor side and got a lot of sweeping but not a consistent lean condition. This seemed inconsistent with the wideband on the other side.
I had done some other parts replacing, ignition modules and temp2, with no luck as well. At that point, I resolved to just systematically check everything, and check one box at a time.
I purchased a smoke machine, they are pretty reasonable now, 150-180 will get you a really good unit. I saw a pretty big leak coming from the driver's rear intake gasket area (also wideband side). Surprised because the idle speed was really not affected, but go figure.
As I pulled off the intake, it was apparent that the rear of the gasket had shifted. I assume during my last installation. Nobody to blame but myself.
With new gasket, AFR was dialed in and no further concerns.
The '85/'86 intake manifolds are very prone to warping, especially the '85 and early '86 models that used the paper gaskets, from the factory. The ears where the bolts are pull down, causing the distortion.
I surface the manifolds and use the later metal gaskets with the integral "O" rings. Yes, the gaskets are a bit pricey, but they are very durable and the manifolds won't warp, because the metal gaskets have no "give".
Crumpler,
Bookmarked this thread for future reference...lots of good data for 85/86.
Can you post a link to the smoke machine(s) you referenced, and make any suggestions?
I think it is about time to buy one and get down to some serious fine tuning of vacuum issues.
-Jason
Just read through this and I had the exact same issues on my 91 GT SC. Ended up being a pretty good vac leak around the injectors. Sealed them all up and everything went back to normal.
Glad and you found it.
Thank you sir.
Originally Posted by GregBBRD
The '85/'86 intake manifolds are very prone to warping, especially the '85 and early '86 models that used the paper gaskets, from the factory. The ears where the bolts are pull down, causing the distortion.
I surface the manifolds and use the later metal gaskets with the integral "O" rings. Yes, the gaskets are a bit pricey, but they are very durable and the manifolds won't warp, because the metal gaskets have no "give".
I don’t know, I replaced a lot of parts first. That probably nullified any impressive behavior on my part.
I should have just smoked the car at the first mention of “lean”. I managed to tell myself that if it had normal vacuum readings and normal RPM, that I didn’t have to worry about a leak.
