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Im having a issue with detonation trying to figure out if its mechanical or in the tune changed out alot to no avial including ecu, prom, dizzy, ecm, knock sensor, plugs, cap, wires, map sensor, tps I have two short data logs on tuner pro that show the issue, when the car is under load at around 2-3k rpm 80-100kpa Im getting detonation with noticeable ping I dont understand why because Im running 93 octane and the conservative aujp spark table any help appreciated
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
What engine?
What set-up?
What car?
What's what?
350 with 195cc intake runner aluminum head 10.8-1 compression, 203 210 duration .480 lift cam, stealthram intake
700r4 3.23 rear 2800 stall 9 inch convertor, wiring ecu is all stock 7730 set up speed density
92 fbody camaro around 3100lbs
I also checked for fuel pressure at idle and at drive along fuel filter was also changed during current diagnosis
Re: Issues with detonation tune or mechanical? $8D
Just looked at your logs quickly.
You are getting a lot of knock retard (KR), I see as high as 20* when commanded SA is 20*. That means 0* of SA (back to initial advance)!!! O2 sensors voltage when in PE indicates high 800s low 900s. So it's not lean.
If you hear audible knock, you have a real problem.
Just glancing at it, knowing you threw a bunch of parts at it, without knowing what set-up you have or what tune you run, I can only say that it seems to be a mechanical timing issue. ECM commands 20* SA, but what do you really get at the balancer (timing mark)? You could be getting way more and that's why there is knock.
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
had same setup but with 170cc runner heads 10.5-1 compression with no issues only change was it sat for three years and changed the heads and torque convertor...
"trying to figure out if its mechanical or in the tune" To me, your statement means you also changed the tune
"changed out alot to no avial including ecu, prom, dizzy, ecm, knock sensor, plugs, cap, wires, map sensor, tps"
That's a lot of changes!!!
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
"trying to figure out if its mechanical or in the tune" To me, your statement means you also changed the tune
"changed out alot to no avial including ecu, prom, dizzy, ecm, knock sensor, plugs, cap, wires, map sensor, tps"
That's a lot of changes!!!
thanks for your input I have a few of these cars and multiple spare parts so it wasnt to much work or investment
I started with the tune I had previously which ran the previous combo and lowered the timing a few degrees and added fuel in the VE at 2000-3200 from 50-100kpa
the car is gutted drag/weekend driver no ac no emission tubular k member and arms ect
Re: Issues with detonation tune or mechanical? $8D
Im not educated much with reading and diagnosing the datalogs yet but have the burner and datalog cable to be able to datalog and make changes I need some input if Im running super lean to cause the detonation from the the bigger heads if i need to dig deeper with the tune fueling I was able to run the previous combo on the stock aujp prom it would only rarely lean pop
this is the current bin im working with some mild changes to a AUJP bin
gonna read now your posts are always educational swapped in a different knock sensor before creating the thread but unsure if i put in a 305 tpi or 350 both are the same 3.9 ohm, car sat for three years so thats why im throwing the sink at it
Re: Issues with detonation tune or mechanical? $8D
I’ll take a look at your tune
Can you confirm:
initial timing?
Engine exact size?
Injector flow rate?
What fuel pressure your injectors are rated at?
What ICM module do you have?
The injectors data sheet?
Thermostat deg F?
AIRS deleted?
EGR deleted?
CCP deleted?
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
gonna read now your posts are always educational swapped in a different knock sensor before creating the thread but unsure if i put in a 305 tpi or 350 both are the same 3.9 ohm, car sat for three years so thats why im throwing the sink at it
305 and 350 use different knock sensor. '92 model with '730 ecm, the ESC module is part of your EPROM. The knock sensor has to be matched to the engine and EPROM. You can not mismatched them. Knock sensors are tuned to the engine bore.
There are good threads on TGO about this topic.
Personally, on a drag car, I would get rid of the ESC all together. They were made for OEM set-up.
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
I’ll take a look at your tune
Can you confirm:
initial timing? 6 degrees
Engine exact size? 350
Injector flow rate? 28
What fuel pressure your injectors are rated at? they are stock gm injectors off a 96 C4 corvette
What ICM module do you have? i have two GM ones
The injectors data sheet?
Thermostat deg F? 180
AIRS deleted? yes
EGR deleted? yes
CCP deleted? yes
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
According to your logs, when in WOT in PE the engine was not lean in the rpm range you recorded.
Quickly looking at your BIN, your fan#1 is set at 181.4DegF. That does not match your logs!!! Fan is not activated when CT is at 210DegF.
you are correct upon driving longer im also noticing running hot over heating the car is using stock fans both can come on manually with a switch one comes on auto with the ecu
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
you are correct upon driving longer im also noticing running hot over heating the car is using stock fans both can come on manually with a switch one comes on auto with the ecu
In one logs, the Fan is not on and in the other one it is. Both are close to 210Deg F. The fan should have been on since 182Deg.F. So why is the fan not coming on? That's the question.
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
305 and 350 use different knock sensor. '92 model with '730 ecm, the ESC module is part of your EPROM. The knock sensor has to be matched to the engine and EPROM. You can not mismatched them. Knock sensors are tuned to the engine bore.
There are good threads on TGO about this topic.
Personally, on a drag car, I would get rid of the ESC all together. They were made for OEM set-up.
agreed the one that came out is indeed a acdelco 350 one, im unsure what the one used for this data log is but can confirm its the same 3.9ohm will try a new 350 tpi one once i get to the bottom of the heat issue but the knock senor was doing it job in this log once audible ping was heard it counted it and pulled back. One thing that i noticed in previous drives was that i wasnt able to reproduce the ping when the transmission was in manual first gear which had me thinking maybe its something with the newly changed convertor causing excessive load to the engine
this is the injector data i found by looking at a lt4 c4 bin file previously was using 24lbs LT1 injectors but still using the AUJP offsets and pulse width
Re: Issues with detonation tune or mechanical? $8D
Might be worth looking at the converter!
Been studying your BIN for over an hour and can't find anything that would cause this major knocking.
Here's a BIN with some basic tweaking. Only use if AC is deleted
VATS disabled
SA Latency Correction adjusted
EGR code 32 disabled
CCP disabled
AIRS 100mv O2 correction zeroed out
VE upper lower table corrected at 1600rpm to match lower table
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
Now I'm out of here, because the wife is looking at me sideways for being on TGO on Christmas day
thank you for looking it over wanted to see if it was a lean condition before diving deeper into the convertor swap yes there is no ac, if you dont mind me asking what is the reasoning you tweaked the spark latency table and zeroed out the AIRS?
Re: Issues with detonation tune or mechanical? $8D
The spark latency table has to be tailored to non-GM HEI control modules. Otherwise you run the possibility of your actual delivered ignition tiiming being considerably off from what you command. There's a process for this if you search on spark latency
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
if you dont mind me asking what is the reasoning you tweaked the spark latency table and zeroed out the AIRS?
If enable, on rare occasion when in CL, ecm will activate air to port and apply the 100mv correction to O2 voltage. This is necessary to account for extra O2 in the exhaust from AIRS. However, I just noticed the AIRS was disabled in your BIN, so there was no need to zero-out. I just automatically do it when AIRS is deleted.
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by SbFormula
If enable, on rare occasion when in CL, ecm will activate air to port and apply the 100mv correction to O2 voltage. This is necessary to account for extra O2 in the exhaust from AIRS. However, I just noticed the AIRS was disabled in your BIN, so there was no need to zero-out. I just automatically do it when AIRS is deleted.
discovered water pump is bad changing as we speak i would of never known it was that hot bc the gauge is pretty off my 160 on dash is actual around 200 on tunerpro log
Re: Issues with detonation tune or mechanical? $8D
ok water pump done coolant flowing now, cant figure out what was wrong with the pump that came off couldnt find anything wrong with it but it wouldn't pump water, temps good now havent had a chance to drive it though, on to the ignition will double check for tdc and meticulously time again. Looked over the ICMs and this is what i have the one on the car currently is 048 7K16 the one that I had previous is a new one need to check the box but it may be 1984A numbers on the underside of the unit probably 4 years old with very little use as three of those years the car sat and I have another one here are pics of the ones off the car
the 1943A is listed as interchanging with 10482827 he states that 10482827 is the 048 ICM
the latency's sbformula gave me are as follows do his numbers compensate for a ICM that retards or advances?
213.64
274.68
305.20
244.16
274.68
305.20
259.42
228.90
198.38
122.08
106.82
213.64
274.68
274.68
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
the latency's @SbFormula gave me are as follows do his numbers compensate for a ICM that retards or advances?
213.64
274.68
305.20
244.16
274.68
305.20
259.42
228.90
198.38
122.08
106.82
213.64
274.68
274.68
It's for the ICM, GM#10482827 (D1943A) or "369" or any newer replacement. I have an ICM from JEGS distributor (#555-40006) and it works fine with those numbers. Now, I assumed you had a '92 style ICM. So don't use the tune I have attached obviously, if you have a "048"
You will find all kinds of incorrect information. Everyone here is a volunteer that is trying to share what they "think" they know. No one has all the answers. This is open source information... FREE!
You're best bet is to do your own SA testing with good ole timing light and a modified tune that locks SA to a fixed value. Maybe you could add your results to the thread:
Counterintuitively in regards to your problem, it actually retards timing. But, if it's malfunctioning too, who knows what it could be doing.
Right now im going to be pulling the alternator and valve cover off to get TDC and the initial timing as perfect as I possibly can Im hoping something is way off with it to explain and cure my audible pinging, In the mean time I have another properly running stock 1992 camaro with the L98 I want to test the D1984A ICM curious about what that will do after reading the latency thread more so than getting the other car running right
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by BHR
350 with 195cc intake runner aluminum head 10.8-1 compression, 203 210 duration .480 lift cam...
93 octane ranges up to 12:1 compression, but this is highly dependent on how much charge your cam is bleeding off on the exhaust lobe, as well as any hot spots being prevalent with 10:8 compression. First thing you should have done is pull plugs to verify it is really detonating. If so, and if VP octane booster doesn't help your 93 octane at 10:8 compression, check to see if your balancer slipped and is giving the wrong Initial/Base reading. If the balancer is okay, then either your 93 octane is not really what it is being sold as, or your static compression is higher than what you think it is. A timing light will confirm latency at idle and part throttle, you just have to be daring enough to check wide open throttle under the hood. I didn't look at the logs, but if its only detonating up top it may be latency related. But if you're seeing knock retard at idle when cold, warm, and hot all over the place, then I'd be looking for a slipped balancer, fuel content, and static compression (run a compression check to get an approximate range). With the latter, a compression check of over 200-psi plus will underline this if so. If cylinder compression is within an acceptable range, then it has to be the fuel itself, excessive static or base timing related... especially if someone already confirmed that the datalog is pulling upwards of 20* of timing...
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by Street Lethal
93 octane ranges up to 12:1 compression, but this is highly dependent on how much charge your cam is bleeding off on the exhaust lobe, as well as any hot spots being prevalent with 10:8 compression. First thing you should have done is pull plugs to verify it is really detonating. If so, and if VP octane booster doesn't help your 93 octane at 10:8 compression, check to see if your balancer slipped and is giving the wrong Initial/Base reading. If the balancer is okay, then either your 93 octane is not really what it is being sold as, or your static compression is higher than what you think it is. A timing light will confirm latency at idle and part throttle, you just have to be daring enough to check wide open throttle under the hood. I didn't look at the logs, but if its only detonating up top it may be latency related. But if you're seeing knock retard at idle when cold, warm, and hot all over the place, then I'd be looking for a slipped balancer, fuel content, and static compression (run a compression check to get an approximate range). With the latter, a compression check of over 200-psi plus will underline this if so. If cylinder compression is within an acceptable range, then it has to be the fuel itself, excessive static or base timing related... especially if someone already confirmed that the datalog is pulling upwards of 20* of timing...
- Rob
its really detonating i can hear it from in the car, checked timing now with a stop to get it perfect it was off but its off in a way where TDC was really 10* after top dead center, haven't timed or drove yet only made the new TDC and 6* before marks
it was detonating at mid throttle while in 4th gear or in load while locked up and going up slight hills from 2400-3000 i let off or the car would die down due to timing being retarded from the audible nose. It was not do it while in manual 1 going through the rev range from idle to 5k with even more foot pressure on the pedal. Im not going WOT due to the convertor being new, yank states to drive 150 miles without going WOT, in the two short logs im in part to mid throttle with my foot pressure even though kpa says 90-100
you have seen my setup when it was lt1 its capable of 10.8 with 93 Im now LT4 reversed cooled
Re: Issues with detonation tune or mechanical? $8D
I remember... that was a few years back. Yeah, when we're above 10:8.1 static, if we swap from one cylinder head to another the quench and the shape of the chamber is very crucial even if the heads share the same cc. It can even be the plugs (tip projection) if you freshened them up, as well as the head gaskets if they were replaced with a shorter compressed thickness. So many variables.
Re: Issues with detonation tune or mechanical? $8D
Originally Posted by ULTM8Z
Ok, I'm thoroughly confused by your setup... Lol...
A LT1, with a conventional distributor, what looks Stealth Ram, and running it with $8D (assuming a 7730 ECM)?
Water pump working, initial timing set to 6* before it was somewhere 4-7* after TDC, much less ping but still does it under load but with the aujp prom. Seeing that the added timing from the base timing adjustment helped I then loaded the LT4 spark table and LT1 VE table to AUJP bin this eliminated 99% of the audible ping it only does a single faint ping now while in lock up but at much higher speeds 70-80mph. It seems the low spark table from the AUJP combined with my retard base timing is what was causing my initial problem from the data logs above so Im not sure the noise Im hearing is from high timing detonation, what Im doing in all the test drives to get the noise is forcing it, giving and holding the throttle to stay in 4th locked up. My question now would be what other spark tables should I transfer over or adjust in 8D from the DA or EE bins? I quickly skimmed through and saw that 8D and EE share a few other tables like closed tps SA vs rpm and startup SA vs coolant.
Re: Issues with detonation tune or mechanical? $8D
There is really no go to timing table. IMO the LT1 is more aggressive than the LT4, but both will work fine with a 11:0.1 compression engine so long as mechanically everything is in order. We just wrapped up a similar situation, a high compression 383. The initial timing would not coincide with total timing needed, resulting is excessive pinging everywhere. Turned out the owner bought the wrong spark plugs (tip projection), and he needed a colder plug. Spark plug change corrected the issue, now the pinging is slight, and not even noticeable with the correct fuel. But to answer your question, a 10:8 compression with that cam should have around 10* Initial, and 24* idle. Start at 35* wide open, and 45* cruise, and just blend it to where you need it. Again, there are no predetermined timing tables. Just give the engine what it wants.
12-24-2023, 04:52 PM
