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High knock-runs like crap.



Ok.. so the car ran good on normal gas, you switched to E85 which means you needed larger injectors and changed tune as well. Then it ran bad, you went back to super unleaded, switched injectors back and tune ...and it runs this bad.

Did you do wires, plugs or headers anywhere in this mix? Kinda sounds like cracked plugs, wrong firing order or something along those lines if something internal isn't going south.. How about a vid of the engine running. We can often hear a lot.
 
guess my cars special. no misfires ever. not one of the other cars ive tuned local had misfires either.

only reason for random misfires is due to a aftermarket cam at idle, why you delete the p0300 code. stock cams dont do this. even with rockers.

if he had misfires before hand dont ya think he'd have know that?
 
Did you change the plugs with the E85 conversion? When I first got my '01, I did plugs on it immediately and didn't realize that I cracked an insulator (maybe it was already cracked and I didn't notice it). I bashed my head off the wall for weeks trying to figure that out. If you did them at the same time, and THAT'S when the problem started, I'd say Bill might be onto something.

Is it possible it needs a CASE learn? Constant knock and misfires sounds like the sensor being out of variance. I had something similar happen on my '98 where it had a weird knock problem halfway through the powerband which turned out to just needing a CASE learn after swapping engines (and CKPS).

What all did you do exactly when you swapped to E85 and the problems started?
 


The Delco wires are less than 6 months and I was running 104 iridium with this issue and then switched to copper 104 gapped at .050. No change. It does misfire at cruise and high rpm. The ignition module and coils are about 6 months old also. I will upload a video later today of it running and of the aero force showing misfires.
 
Scottydoggs said:
guess my cars special. no misfires ever. not one of the other cars ive tuned local had misfires either.

only reason for random misfires is due to a aftermarket cam at idle, why you delete the p0300 code. stock cams dont do this. even with rockers.

if he had misfires before hand dont ya think he'd have know that?
Click to expand...

Not at idle.
 
rickisrad said:
The Delco wires are less than 6 months and I was running 104 iridium with this issue and then switched to copper 104 gapped at .050. No change. It does misfire at cruise and high rpm. The ignition module and coils are about 6 months old also. I will upload a video later today of it running and of the aero force showing misfires.
Click to expand...

What injectors did you replace the stock ones with?
 
I did a compression test and cylinders 2,3,4,5,6 all tested at 170 psi on the same amount of strokes. initially cylinder 1 tested at 130 psi and went up slowly. I unseated the tester and tried again and it went to 150 with the same amount of strokes as 2-6. I unseated 2 more times and they both tested at 160. Looks like all is good compression wise.
 


in the vid, is this a cold start? cause the knock sensors dont do any thing till the engine is up to operating temps. most tunes are set to 90 degrees, then they work.

so if its a cold start, it might be something really off the wall. like a bad pcm maybe or knock sensors.
 
I don't have one on hand. I can stop at Morads and pick one up after work tomorrow. Can I flash it in the car? I have 6 credits left on HPT
 


that crap sucks, new vin and need to unlock it. can you change the vin to your vin afterwards? and idk whats cheaper at this point, credits for the new vin, or just unlock the whole year.

you can always run it on the stock tune on the new pcm to start with just to see if thats your issue or not. likely need to do a security learn.
 
Don't worry about the pcm. Some of us tune the knock sensors to come on at much lower temps because the car gets driven when it's not yet warmed up. Look in your bin at what temp they are enabled at before we condemn it. Also, I've seen a couple of cars that showed misfires at idle on the aeroforce. Usually didn't continue when driving and didn't run bad, so that's different in this case.

Agreed on the case learn. I've had a couple of jobs where the car ran horrible until I case learned it. Never hurts to do one.
Your wires going to the back look very tightly pulled. Please address that.
When the headers went in.. did you pull the plugs or install with plugs in? If you installed with plugs in, throw your plugs away.
Please verify firing order, seriously you should honestly do it. Can't tell you how many times I was able to swap a couple.
Do you have an exhaust leak? Couldn't hear very well on the vid.
Might be worthwhile taking the case off the phone and doing a fresh one. This time, don't spend a second looking at the aeroforce, just start the car and let's hear the engine from the engine bay.
 
It is set for 32*
I will do a case learn and new video tomorrow without the case. I have changed the plugs at least three times since the headers. Twice in the last 6 months. The firing order is correct, I checked. I don't think there is an exhaust leak, at least not a noticeable one. There was one at the new collector but I got that sealed up with rtv copper. I will give the wires more slack. Thanks everyone for the help!!!!




 
ok.. next thoughts.

Has the engine, trans or ps pump ever been out of the car? If so.. jack up the passenger side, pull the splash shield and check to see that the rear knock sensor wire didn't fall on the axle and is rubbing or some nonsense. Another guy I knew had knock issues and we found that the part of the knock sensor where the connector attached was loose. If it's loose, it needs to be replaced. I'd suggest you check both if we don't find anything else first. Also check the front sensor wire in case someone did a starter and somehow biffed it up.

Knock and misfires are based on the pcm thinking the detonation happens at the wrong time. Sooooo if it's not a case learn issue of the pcm not thinking it's firing at the right time, or the crank sensor isn't full of metal crap (it always happens) or the rings on the balancer aren't loose/bad. Well... at that point we'll be needing some more ideas.
 
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