LOW BOOSTING & KNOCK... why?

[1QWIK6]

LOW BOOST + KNOCK + MAXEFFORT = PROBLEM!

MY 87 T will knock at 1-4 PSI BOOST! WHY?

Stock block, M&A heads(FR3LS1? plugs), 72# inj, 2 307's, MaxEffort Chip. (22* timing) 100 Motor Octane fuel. F/P 38 PSI (raises 1 PSI per # of boost). 165 coolant temp.


When crusing around, and I need to pass someone, I slowly ease into the gas and look at my scanmaster and start to see knock. (1-5*). I don't know if it goes away or not, but it shouldn't be there in the first place!

Can someone help me diagnose this problem?

Thanks

 

[TRENT THOMPSON]

could be false knock

 

[blackbuick87]

Put some 110 in it and see if it goes away. If not it is false or a bad sensor

 

[1QWIK6]

Hmmm... I dunno. I blew a headgasket before thinking it was "false knock".


TTT

 

[TT/Ameasap]

Sounds like false knock like Trent said.

Check your downpipe and motor mounts.

HTH
Bo

 

[1QWIK6]

I dunno about the false knock... I can understand if I was launching the car from a dead dig, but the car is in motion, and I slightly ease onto the gas... nothing should be moving to cause false knock.

TTT

 

[BJM]

Are your injectors known to be good? A really clogged one might go very lean and cause knock.

Does it drive normally up until knock occurs?

 

[TR Custom Parts]

Having the same problem here. Easing into some boost and my Caspers knock gauge lights up to the red but NOTHING on the Scanmaster though.

Last nite I pulled out of my driveway and had to get on it pretty hard to get into traffic and let off abruptly and had a big backfire, what the heck would cause that?

 

[1QWIK6]

I'm not sure about the injectors being totally clean. BUT once again... this is a LOW BOOST issue. I have 72# injectors, just easing into the throttle probably is not an 'insufficent' injector fuel issue.

The car starts, runs, idles, drives just fine. When I start to put the engine under a load (AKA boost). I see the SCANMASTER start to see knock (1-5*). REMEMBER: I am just EASING into the boost.

BuickGn Boosted: Backfire out of the intake is a LEAN fuel issue.

 

[motorhead]

22*???... Hmm... there could be an error in the timing map... initial & total timing could be waaaaay out of whack. Try another chip.

 

[Steve Y]

hmmmm

Well, go up on the FP to 42 then go up 10 on the cruz fuel.

See what happens.

With injectors that size you could have 1 running lean at low PW.

Need to look at your PW at cruise and when you get a chance send the injectors out to get flowed.

Steve

 

[TR Custom Parts]

Actually the backfire was coming out of the exhaust and forgot to include that the car was not warmed up yet when I got on it. Was a matter of sheet metal survival, had to mat it to keep from getting hit by a guy that was determined not to let me out into traffic.