Fuel Pump Getting Weak?

[Scoobum]

Jason, I'm gonna tap into the wire behind the ALDL...and try and get the SM working again...and I'll make sure it's seeing 12 volts. If it's fukd I'll have to learn how to adjust fuel/timing via PL.

[Scoobum]

Okay...just got off the phone with Jason. Last week when I added fuel to bump the 02's the WOT BLM's are pegged at 142. An earlier file for an 1/8th mile blast from this year shows the WOT BLM's in high gear at 120. I'm seeing runs in high gear of 120 to 124...normally ...on default fuel. This thing's now throwing a crapload of fuel at it in high gear...correct? Jason and I both think that the 02 sensor would have to see a huge pre turbo exhaust leak. My gut tells me the ECM is fukd. Chime in guys...put your 2 cents in.

[Steve Wood]

yep, it is obviously adding fuel.

As your fuel pressure is good, then it would seem to be either a bad O2 sensor, or a leak.  Strange thing is that exhaust leak affect tends to diminish above 3000 rpm because the exhaust pulses are closer together and there is less time for air to be drawn back into the pipe.

I know you just changed the sensor because the difference in O2s at idle which seemed to go away when you put the new Denso in, but I would be tempted to swap again.

I guess I would check the pcv valve and make sure it is still working as well as check under the turbo mounting flange to make sure it is not blowing out big time there...as well as the headers themselves.

be sure the vacuum block is still sealing to the plenum, etc.

[nocooler]

I assume you've disconnected/reconnected the ecm, reseated the chip, is the maf locked at 255 on that chip? Vent line plugged so the fuel tank can't breathe?

[Scoobum]

I assume you've disconnected/reconnected the ecm, reseated the chip, is the maf locked at 255 on that chip? Vent line plugged so the fuel tank can't breathe?

Jeremy, the vent line looked fine when I had the tank down to swap the pump. Battery was disconnected for the pump swap. MAF is locked at 255...it appears the same from files before and now.

[Scoobum]

yep, it is obviously adding fuel.

As your fuel pressure is good, then it would seem to be either a bad O2 sensor, or a leak.  Strange thing is that exhaust leak affect tends to diminish above 3000 rpm because the exhaust pulses are closer together and there is less time for air to be drawn back into the pipe.

I know you just changed the sensor because the difference in O2s at idle which seemed to go away when you put the new Denso in, but I would be tempted to swap again.

I guess I would check the pcv valve and make sure it is still working as well as check under the turbo mounting flange to make sure it is not blowing out big time there...as well as the headers themselves.

be sure the vacuum block is still sealing to the plenum, etc.

I'll order another 02 sensor in the morning...will be here Tuesday. I'll go over the exhaust and intake. I cleaned the PCV valve about a week ago with carb cleaner. If you blow through it extremely hard a SLIGHT bit of air will get through.

[Steve Wood]

Normal, I think

[Scoobum]

Got the SM working. There was a break in the power wire somewhere. DS header and crossover comes off tomorrow for inspection. Dan handed me a pair of gaskets a couple weeks back. Anytime I have a problem, Dan drops what he's doing and opens his shop doors or hands me any spare parts he has to keep me going.

[motorhead]

Not apples to apples. But, the wagon went lean all of a sudden at WOT at the track a few weeks back, and I couldn't figure out why until today.  Stuck a pressure transducer on it and saw the pressure drop 10% (6psi) - that makes small injectors, dangerously small injectors.  The Error % between Commanded Equivalence Ratio and WBO2 is representative of the lean condition.

For your power level you really should be logging more data.

[Scoobum]

I've run this combination for years...and it's run nails. I'm having a run of bad luck. Inspected the turbo flange gasket...it's fine. The DS header weld looks like it's hanging in there after 15 years...can't see any cracks. The gaskets around the plenum etc appear okay. The header gaskets appear okay as well. I can't hear any exhaust leaks. I was under the car a couple weeks back and had my hand around the header flanges and couldn't feel any leaks. I'm kicking myself in the ass I didn't have the spare ECM with me.

[Scoobum]

Steve...if you go back a few replies you'll see I swapped out to ANOTHER new 02 sensor at the track...and I said no change. I'm trying to jog my memory if I swapped it after the first or second run when I bumped up the boost to see if the fuel pressure followed. What I CAN tell you is when I swapped it out and fired it up...the 02's hovered in the 760's for a minute or so...and then went into the 850's and stayed there.  I was so pissed off I honestly can't remember.

[Scoobum]

Here's the game plan for Friday. At Steves request I ordered another Denso 02 sensor. Arrived today and I installed it. Broke out the spare ECM and got it working with PL. If the car comes up short for 02's with the new sensor...then I'll swap the other ECM in and give it a whirl. One thing I learned early on with these cars is make one change at a time. If that doesn't fix it...then we'll toss a Molotov cocktail in it and break out the marshmallows and wienies.

I've never seen this car push me like it has the past 4 weeks. I cleaned off the PC board on the other ECM...installe d it...nothing. Pulled it back out and cleaned it again. Install it...and it says trouble codes across the top. I call bullshit...act ually, I yelled it. Check the SM...no MAL codes. Hit clear codes on PL...no go. Shut PL down...restart ...same shit. Restart PL...no codes...and the graphs start moving...all good.  Fuck I hate these cars...

[Steve Wood]

You need to 1)  Take a deep breath 2) Put a case of wine in the trunk/boot  3) put the G/F in the passenger seat 4) Drive west til you find a mountain with 12 hrs of sunshine 4) Stay there until the wine is gone....all will be right for those with a case of wine in the trunk.

[Scoobum]

After four 02 sensor changes...the high gear fuel and BLM's returned to normal. The three other 02 sensors I swapped I purchased in bulk a few years ago...and forgot about them. If I was a betting man. I'd say there was a bad run of them, and I just happened to buy a few. Thanks for everyones help.

Hot lapped the car this morning for 3 runs to semi get a bead on it for Round 1. Had to pretty much guess for a dial...and was a tenth off...and went out in Round 1.

[nocooler]

Glad you got it sorted out!