plugs. coils. lash adjuster/ head noise. just depends

 

I use the iat adder table to subtract timing from 140 on up incase of H/E pump failure. Under 140 == 0.



Ruled out plugs.
I would think bad coil would be giving misfires, which im not experiencing in my logs.
Lash adjuster/head noise is possible. But with only 55k miles on the car I would be highly pissed at GM...

 

Also bro last time i had my lsj i had a similiar issue like yours... Until i changed wherei got my fuel... The place where i was getting it at was getting a **** load of water in there system along with issues with there pumps sending in the incorrect fuel then chosen!!

 

Your PCM could have KR memory. Disconnect the battery for 1/2 hour and try it again.

 

good point. kinda spaced that one out lol

 

well I have gotten fuel at a few different places, and it didnt seem to make a difference in the KR. Shell, Marathon, Sheetz (yuck). havent tried sunoco in a long time, but they dont have 94 anymore here, just 91 and 93

Seafoam seems to have made the biggest difference yet. but not a solution to the problem.

I appreciate the input

 

More test results.

Fuel pressure is steady at 62psi while not under load.

Spark plugs changed to NGK BKR7E and gapped at .038. Was using Autolite 3922 @ .035

Data logs show a weird spike in afr around 6100rpm. jumps from 11.3 to about 12.0 for a split second, then back to mid/low 11s. So I tweaked the maf to add more fuel in the cells where it leans out.

Still havent found a leakdown kit. Going to look up how to do the valve lash adjustment since a couple people suggested that.

 

what lash adjustment.. hydraulic..

its not fuel

find a leakdown kit..............

when u scaled the maf up a bit did it get rid of the spike and did the KR change or is consistently in same rpm/ load range

 

and i know ur tune hasnt changed but have u checked for boost leaks?

 

.038 is a pretty large gap. With your mods you'd probably be better off around .032...

 

I just realized that the lash adjusters are hydraulic after looking at the gm service manual.
I havent driven it enough to tell if the maf re-scaling solved it. it is consistently in the same rpm, gear, and load.
As for the Leakdown, either I will have to buy the kit from summit, or pay the GM garage to do it. I have not found any shop or person with this equipment. And the stealership I go to wants $80/hr labor to do this, so it looks like I'm heading to summit. If I need to I will just sell the leakdown gauge and make most of my $ back.

no boost or vac leaks. fuel trims are deadnuts.

I have played with all gaps from .032 to .038 with both ngk and autolite plugs. Yes, .032 does seem to work better although it runs a bit richer.

 

The maf scaling helps, but it still wants to go slightly lean up top. Just not as lean now.

Still searching for a leakdown kit...

 

i thin the problem is mechanical

 

Going from 11.7-11.8 down to 11.3 will def show a bit of a power loss. That combined with the shitty winter gas that is already out will drop the power. It isn't WAY off making me think motor trouble. Does it still pull all the way to redline or die off hard up top?

 

Just make a leak down kit. Find a regular compression tester that has the gauge threaded on, unthread the gauge put a t in and add a schrader valve (tire stem). Done.

 

Just pull the valve cover off and take a look at the inside to make sure nothing has came loose or moved pretty sure something is off in there

 

It pulls hard to redline in 2nd gear. 3rd and 4th have no *****. This problem has been since July, so there was no winter gas in the mix then.
I only went to 11.3 to quench knock. it actually feels like it "hits" harder with teh richer afr in 2nd gear.
I shoulda known something was up when it took 20* of timing to break 300whp. However the car didn't complain and pulled HARD. Just now that I see people easily over 300 with less timing on the tvs and the same size pulley.

Already did. no rockers or lifters floating around. Cams looked smooth and didn't show any grooves or wear.

 

Damnit this blows! I want my ******* power back!

My friend who is a mechanic is strongly doubting theres an internal problem since my compression test was ok. he said a leakdown wont reveal anything since compression is good however he doesnt have any plausible alternative suggestion to the power loss, poor fuel economy, and propensity to knock...

 

You can still fail a leak down test if you have good compression.

 

I'm doing a leakdown this weekend. I'm just gonna go to Summit (hour away) and buy a damn leakdown gauge kit since nobody seems to have one I can use. Even if it passes atleast it will be one more thing I can rule out and be one step closer to solving my mystery.


I realize all my work will probably be a waste of time when I find the solution and it ends up being something simple and cheap that I was too stupid to think of.

 

Really Odd for sure, hope you get this solved.

 

prob not your issue but back in august I too was getting KR yet nuthn has changed since I last tuned. **** was driveing me crazy seeing 6-8* of KR...So I figure I would try and adjust my tune, yet it wasnt resolveing any issues...It ended up being the meth injection filter, was clogged just enuf to throw tune way off. Removed the filter from the checkvalve and all was back to normal. Now I keep extra filter in tool box for when it happens again. I feel your pain, hope you fig out.

 

maybe fuel filter issue then

 

More ******* Problems. Car doesn't want to start after cam removal. Cranks, belches smoke from exhaust, no haz turnover. But if I reset the ecu by disconnecting the battery, it will fire after 2 cranking cycles and run smooth as butter and does NOT throw any CEL Drove it around about 10 miles, parked it, shut it off, same thing. Cranks and wont start.

I figure it has to be either the engine is out of time (not likely, I checked the cam chain) or the cam position sensor is screwing me. However I thought if either of these were true it would throw codes...



However there is good news. There is almost zero leakdown in all 4 cylinders

 

cam sensor.

replace ur fuel filter too btw.. and whyd u remove ur cams??