Techno Duck

I will openly admit i am a major dumbass once again on this forum. I pulled the fuel rail to swap injectors #1 and #2 to see if the lean plug condition followed. And what do i find? I put the #2 intake gasket on upside down when i put the manifold back on last after my turbo swap. Whoops! . No doubt it was because i did that in the winter and was freezing my *** off. I wonder if that was causing the lean #2 plug...

There was about 9k miles of mostly conservative driving (12psi) and 1 track day. Hope i didnt do any damage!

As for my rich running condition, i have a new wideband sensor ready to go on once i get the manifold back on later today.. .

TurboTommy

You did say you pressure tested the intake, which would have shown itself up as a leak, there at the #2.

Chris White

I would guess that the only damage is from hitting yourself 'upside the head when you saw the gasket....

Techno Duck

Whoops..



All fixed now, luckily i decided to start 'stocking' intake manifold gaskets .

Cant believe the car was running fine for the most part all this time with the injector port 1/4 of the way blocked. And the gasket sealed fine all this time, no leaks at all! The last time the turbo was removed the same thing happened on the #4 cylinder by the shop that did the work, that gasket was blown out in a big way when i pulled the intake off.

fast951

I have seen a race engine, built by a well known shop (big $$$) come apart on the track, cause "upside down intake gasket! the fuel was hitting the gasket, and the rest is history".

If no damage was done by now, you were lucky!. You might want to check the AFR with the existing sensor after you fix the gasket.

Black51

I thought you were trying to sell your car. Why are you pulling the engine this winter and putting on new parts?

Techno Duck

Lets just say i came to my senses after the road trip out to 944Fest a few weeks back.

Black51

Ah, he came back to the light!

Techno Duck

Its pouring rain out now, but i am planning on cutting the DME temp sensor connector boot open to check the wiring. I played around with the connector yesterday, mainly adjusted its routing around the charge pipe and coolant pipe. The wiring was folded in two areas the way it was originally routed pretty tightly, so i want to cut the sheathing and boot off to see if the insulation on the wires is still intact or not. The car ran fine the 2 miles to my friends shop, on the way home however the car was running rich, in the 13-13.5 AFR range at idle. Exactly as if the car were still in warm up mode. This morning the car ran fine, but is still rich on boost.

I swapped the wideband sensor yesterday and still get the same rich running. Basically from 0-5psi i am in the mid 11's already where previously it was in the mid to high 12's.

I think it could be possible under load conditions the DME temp sensor or associated wiring might be acting up causing the car to run rich on boost.

Another thing i was thinking about is the possibility the TPS is giving incorrect throttle angles leading to it running richer than it should?

Here is a recap on my 'issues'.

-Car runs rich on boost. From 0-5psi its already in the mid 11 AFR's, previously it was in the mid 12's. This is only giving it part throttle.

-At full boost (13-14psi is where its currently set) the car runs much richer, dipping down to as low as 10.8 AFR with it mostly in the 11.0-11.2 range. Previously it would run 11.2-11.4 AFR (normal considering no piggyback).

This may or not be related, but occasionally after cruising at constant speed for 5-10 minutes the car will stumble and overall feel very laggy on normal acceleration through the gears. A possibility i was thinking hear is the car could be pulling timing from the knock sensor or associated wiring which could be faulty. I need to pay better attention to the AFR's when this happen, but as i recall they are never far off where they should be, just the car is very sluggish. I dont actually know what the car would feel like when it pulls timing though, so maybe i am incorrect here. This has been a problem for a long time, but only happens occasionally after drives cruising at a constant speed.

So my plan of attack is to replace the DME temp sensor and check the wiring at both the temp sensor connector and TPS whenever it stops raining. This will be followed by pulling the intake yet again to replace the fuel injector, crank sensor and ISV / other associated wiring harnesses when i get home again. While the manifold is off, the knock sensor, TPS and ISV will all be replaced.

Techno Duck

Checked DME temp sensor and TPS connectors. TPS looked good under the boot, the DME temp sensor wires were cracked under the boot. The picture looks worse than it really was as i peeled off alot of the crumbling insulation before hand. I soldered in a new section of wire for the time being and saw no effect in how the car runs at all (which also leads me to think they were not shorting together in the boot).



Tested DME temp sensor and ohm's are inline with what is normal. 275 ohms on a hot engine.

Tested TPS (on hot engine) and it checks out aswell. 500 ohms closed and 3800 ohms at WOT

Running out of ideas on things to check. Think i may pressure test the intake again to make sure i did not miss anything.

So far this is what i have done to figure out this rich running situation.

-Check TPS and wiring
-Check DME temp sensor and wiring
-Clean MAF ground and checked voltage between MAF ground and negative terminal on battery.. 0v ignition on or off and at full electric load (HL, fogs and driving lights on).
-Check fuel injector harness, 12v on both pins with ignition on
-Pressure test intake system to aprox 12psi, bypass leaking thermovalve. No other leaks found
-Replace ignition coil, replace ignition wires, replace spark plugs NGK BPR7ES @ .28 gap
-Check distributor cap and rotor; not melted or burned up. Both have less than 5k miles on them.
-Replace wideband sensor

What i need to do..
-Clean MAF sensor, 13k miles on it.. inspected about 2k miles ago it looked spotless inside. Besides i figured the car would run lean, not rich from a dirty sensor?
-Check fuel pressure (no gauge yet unfortunetley).
-Check 3-bar FPR, has 14k miles on it and is 2 years old. New fuel rail and adjustable FPR being installed when i am home again.

Any other ideas? I am trying to think back to the first time i noticed this but frankly i cant remember if this started happening before or after my trip out to 944 Fest. What really gets me is nothing really has changed since i last drove the car (with normal AFR's) back in May/April. I did put the SFR FMIC on in i think early May, but the car was running great prior to that.

toddk911

We are talking about .5 a/f difference from your lean to now rich.

A. I would not be all that concerened with this small of a difference and if so, it is on the richer side, not leaner so no worries.

B. If you are really concerned, just lean it out a bit and then worry about it in a few months when you pull the motor, etc.

Techno Duck

10.8 AFR's at WOT.. dosent seem right to me. A band aid fix to just 'lean it out' and hope for the best.

After playing around with a few things yesterday, i grounded the MAF directly to battery, grounded wideband controller and gauge directly to battery and powered wideband directly to battery (fused of course). No effect. I thought about it a little and my rich AFR's follow when going WOT.. goes from 11.2-11.4 AFR to 10.8 almost immediately when going from say 50% to WOT. I think this pretty much completely rules out the stock O2 sensor, TPS and probably DME temp sensor as the culprit. Which leaves me with intake leak (pressure tested twice.. only leak remaining is very small hardly noticable leak at 15psi on throttle body), fuel pressure issue or weak ignition (no other symptoms of weak ignition..and every component has less than 5k miles).

I was talking to my buddy about the exhaust leaks when it dawned on me. I think its possible the downpipe to midpipe flange which is leaking a huge amount could be the cause of the richer AFR readings. The copper gasket is completely shot as its been reused atleast 4 or 5 times now with about 35k miles on it. Ive been reading that post turbo, pre-wideband leaks usually cause the wideband to read lean as its sucking in extra air through the leaks (sorta like scavenging). I think its possible that my leak is bad enough that there is no scavenging effect sucking in air as the exhaust is leaking straight out rather than pulling air in causing my overly rich AFR's.

I just ordered a new gasket through FabSpeed (very helpful guys) and will put it to test tomorrow.