Tuning saga.. tuner said possible bad PCM?

Mild combination - 1998 firebird, 241 stock unported heads, fast 92mm intake and NW 92mm tbody, cam (.588/.595, 228/232, 114 LSA), 1 7/8 headers, alum flywheel.

So first tuner had car running like crap for anything but WOT. It would always go to PE table and cruising around 10:1. Gave him 2 chances to correct it but he didn?t give a crap.

Second tuner (after weeks with the car) said he had car running great. But on the next night says he says its getting 4 degrees KR and found knock sensor error code and figured he changed the knock sensors. While doing that, he saw the knock sensor wiring harness crimped in between the transmission and the engine and said that was causing a short and triggered the error code. So he put in new harness and continued tuning. Said he said that now it?s running great again and come pick it up. I come after work the next day and his O2 wideband is still attached to my car ? I asked ?whats up because I thought it was done?? He said he wants to finalize the tune with me in the car. OK whatever? We go for a cruise on highway and now he is seeing KR at WOT. After an hour driving around and him lowering timing and adjust MAF table, he can?t get rid of it and tells me to :

-take it home and
-swap out the plugs because maybe running on the old tune for so long fouled them
-maybe the pinched knock sensors wiring harness broke the PCM
-log more files at home

So yesterday I log more files and get KR anytime I got WOT. Logs attached. Note: The a/f in the logs in skewed because I think I didn?t set it up right in HP Tuners but my in car wideband shows pretty solid 12.5 at WOT. The logs show about 13.4 at WOT but I?m pretty sure the logs are off and my wideband is right on.

I will swap plugs soon and re-log but I think new plugs will only make it burn better and leaner which could exasperate the issue if its caused by leanness (which I don?t think it is).

I have a call in to tuner today and I know he?s gonna push replacing the PCM but I think that is bogus. Car runs great around town, very close to 14.7 while cruising.

My thoughts:
I?m fairly certain he started my tune with a base 98 calibration and tweaked it from there..
-My car has 5 wire 85mm c5 z06 MAF and his MAF table looks very close to stock 98 table where as for reference, my old c5 cars had lower numbers in that table. Should the 85mm c5 maf require lower numbers in the MAF table (I think 98 fbody and mine are about 36 to 38 but the c5?s I?ve seen are more like 32).
-I don?t think PCM is damaged at all. No codes and no drivability issues. Only issue is KR at WOT. Can pinched knock sensor harness fry a portion of the PCM?

This is really frustrating. Thanks for any suggestions?
Attachment 56165

Attachment 56166

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Attachment 56168

Put some higher octane fuel in it and see if knock retard goes away.

i run 93 exxon/ mobil and just filled it prior to those runs.
Are you suggesting something like 100 octone?

did he use AC Delco knock sensors or aftermarket?

not sure but i'll ask. why? aftermarket too sensitive or something?

They are either too sensitive or they don't pick up the correct frequency for knock. I've ran into this once and have read others having similar problems.

I looked at the log. The knock starts right after WOT which can be an indication of not getting into PE fast enough. If you get knock on intial WOT it normally continues to knock and gets worse the longer you stay WOT.

If I'm looking at your file correctly at WOT the AFR is mid-high 13's. Your PE multiplier is 1.13 and your stoich is 14.42 which puts PE about 12.75. Did your tuner change your stoich? I'd have to look but I think stock is 14.62 for that year(that's what it is at the stock 99 Vette tune I'm looking at). I haven't done it, but IIRC correctly if you change stoich there are some other things you have to change too.

Is that AEM fuel pressure PID accurate?

Commaned AFR Hi Res is commanding 12.72 and actual AFR according to the AEM W/B is 13.31ish.

The MAF transfer table may be the issue and it's knocking because it's lean

or if that fuel pressure PID is accurate(which I can't see how it could be)you aren't getting enough fuel.

upgraded to version 3 and did some logs.
Used a better adjustment (preset in the new version) for af so you can see its running mid 12's. If fuel pressure was low, i'm thinking I wouldn't be able to be at mid 12's at WOT. I"ve checked fuel pressure within the year on dyno and it was at 60.
Still getting up to 4 KR.
roads covered in salt so only took it up to 70.
didn't adjust the tune at all. seems like sold mid 12's should not be the reason for the KR.
Since MAP was mentioned before, what are normal MAP pressure readings at idle and before giving it throttle? I saw some readings in the 40's at while coasting at low 1200 RPM after the WOT runs. How would bad MAP induce KR? at WOT, the MAP readings look normal to me (~100) and that is where the KR is. still confused

its knocking because it has too much timing in it.. pull some out and it will go away

Quote:

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Originally Posted by VYSSLS1

its knocking because it has too much timing in it.. pull some out and it will go away

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so for a test i did 2 changes, one at a time.
first i lowered the timing across the board 75% like you suggested. hpt file and associated log attached.
The car still got 4 degrees KR.
THe for a second change, i kept the lowered timing but also richened the PE table to be high 11's. hpt fle ("75% less and 1.21 PE) and associated log attached.
still getting KR.
the 2nd log file is short and easy to see the WOT hits and KR.
thoughts?

This might be a stupid question, but you don't have an exhaust rattle or anything do you. For some reason I was under the impression that actual knock retard had a saw tooth pattern or something. This looks purely RPM based to me...

I only ask because That was my issue. On the stock tune no less...

ok well yeah i hear a rattle near muffler. I assume its the heat shield under the gas tank. Been wanting to remove that shield but just wanna confirm gas tank won't explode :) Do you think that small rattle could be heard all the way up there?

It's possible... With the exhaust being one long metal section it is possible that the vibration can create a harmonic all the way up to the block.

I would try and bend the heat shield a little just to change the vibration frequency or even brace it from vibrating and make another pull. See if there are any changes to your KR

check your knock sensor data in your tune against the data in a stock tune for your car, following that check for anything metal banging around like your exhaust, intake piping, belt tensioners, brackets or even internal parts like rockers or springs. this will cause false knock.

If your MAF is the round one like the one on trucks,vans,suvs (should be since to my knowledge that is the only one used on the C5) then your numbers should look like this in lb/hr

12.5870172816179 14.8812026974792 17.4854131695381 20.461653709034 23.7479193047273 27.3442099566181 31.3745356871854 35.7148864739502 40.4892723393914 45.6976932835092 51.2781442950639 57.4166404077741 63.9891715991607 71.0577428804634 78.5603492404425 86.5589956903376 95.0536822301486 104.292428904834 114.213230703153 124.940097647586 136.411024726893 148.750021963553 161.833079335087 175.722201852734 190.417389516495 205.918642326369 222.163955271117 239.215333361979 256.948766576475 275.488264937084 294.957838466286 315.357487164081 337.307261142863 360.435130335195 384.679089729838 410.101144338032 436.639289148537 464.169514138873 492.87783434276 522.702244748958 553.704750368707 585.885351202005 619.554072305052 654.648908666607 691.045850264192 728.744897097806 767.808054178689 808.111311484362 849.840684048543 892.748151826275 937.081734862515 982.779428146025 1029.8412316768 1078.32915046609 1128.36719453636 1179.45932379771 1232.22558836252 1286.60398321956 1342.65651338006 1400.3211738328 1459.84598462271 1521.60297581725 1585.77816245013 1651.31745933028 1719.21294663753 1789.21660432692 1861.32843239846 1935.67244087461 2011.56657463176 2089.01083366989 2168.56326309016 2250.4098779263 2334.55067817829 2421.17167887987 2510.52090007599 2602.66034677788 2697.83803903051 2796.23999186759 2898.11422533408 3003.77076448618 3113.51963438009 3227.85687510573 3346.90649668556 3471.04052918703 3600.75501270006

or if you want to pull the numbers from a stock 2004 Z06 tune they will be this.

11.2849120455884 13.9511275288868 16.6793480234246 19.71759357416 22.6938341136558 25.8560896868702 29.328370316282 33.1726810131308 37.3890217774166 42.1634076428578 47.3718285869756 53.0142846097698 58.9667656887615 65.2912768351901 72.0498230602953 79.1183943415979 86.6210007015771 94.6816521627116 103.610373781199 113.283155534561 123.699997422796 134.798894434666 146.57984657017 159.104858840549 172.373931245801 186.325058774688 201.082251449688 216.521499248323 232.828817204311 249.880195295172 267.799643543387 286.587161948954 306.490770556833 327.75848941198 350.576333548115 374.63427790904 399.994327505994 426.718487350217 454.74475243047 484.197132769231 514.889613332782 546.946204143601 580.304900190451 614.84169145085 650.556577924801 687.57356963478 725.83066156955 765.327853729109 806.251161147177 848.414568790035 891.756071646443 936.585694772599 982.779428146025 1030.52328680044 1079.7552657246 1130.7853899747 1183.55165453952 1237.99205440779 1294.16859459078 1352.20528511095 1412.1021259683 1473.85911716284 1537.5382637058 1603.13956559719 1670.78703285948 1740.48066549268 1812.22046349677 1886.06843188301 1962.14858067388 2040.2128898244 2120.38536935707 2202.91403931684 2287.73689469247 2375.03995051769 2464.76120178124 2557.14866852809 2652.07834073576 2749.98425348292 2850.55638171339 2954.16675549459 3060.81537482652 3170.75025975415 3283.90940526623 3400.47882639648 3520.70654318987

Quote:

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Originally Posted by Crashgnx

If your MAF is the round one like the one on trucks,vans,suvs (should be since to my knowledge that is the only one used on the C5) then your numbers should look like this in lb/hr

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hi - yes the numbers look very close to what you posted. your last amount in z06 file is 3520, and in attached table, it is 3524.

hi again - i made some changes and the KR improved but i'm still seeing it.

Saturday 2.13 changes:
-reduced knock sensitivity from stock 1998 to stock 2004 z06..
-increased decay rate table to .25
-the Cold Power Enrich Enable TPS Threshold vs. RPM. Back to stock (from 10% my tuner).

Sunday 2.14 - as mentioned in this thread, timing seemed high in low rpms. So decreased timing in lower RPMS (just Copied stock z06 in lower areas)

Monday 2.15 change - raised Knock Sensor Level vs. Tip In TPS Copied from stock z06 file. I should have done this at same time as the saturday 2.13 change (knock sensitivity) but didn't know. I have no log files of this yet as i just figured out. I wonder if this would have an effect

New tune attached, as well as log file from yesterday. all pulls in 4th. the first 2 bursts were clean with no KR but the final burst in the log shows 3 instances of KR with the last going up to 1.7.

Thoughts?
Also why is it referencing the low octane table? I separated each table by 2 degrees.