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Old 09-26-2005   #1
george88gta
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engine pings

A while back, I replaced the 305 "F" engine in my 1988 GTA. I used a GM crate engine, 350 CI, 300HP. I had a custom chip made for me by Hypertech. At the time of the swap, I changed to ACCEL 24 lb injectors. I also replaced the EGR valve and knock sensor with parts for a 350 engine, vin "8". EGR controls are the original 305 controls.Car always had a slight ping, but now it is getting worse. It pings when you go from a dead stop until about 2000 rpm, engine hot. The chip was made for a 195 thermostat, gauge indicates 190 - 200 temp. I only use Sunoco or Shell 93 octane fuel. I reset the initial timing back to 0 degrees and it still pings. Fuel pressure is adjusted to 48 psi. I also ran some GM top cylinder cleaner thru the engine, but no improvement. No check engine codes. One other thing, the fuel around here contains 10% ethanol. Did I screw up by switching to the 350 EGR valve and knock sensor? Any help would be appreciated. Thanks.
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Old 09-26-2005   #2
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: engine pings

What is your total timming set at?
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 09-26-2005   #3
george88gta
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Re: engine pings

Quote:
Originally Posted by fearthisgta
What is your total timming set at?
Not sure how to check that. When you reconnect the timing disable wire, the timing goes past the end of the tab.
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Old 09-26-2005   #4
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: engine pings

Quote:
Originally Posted by george88gta
Not sure how to check that. When you reconnect the timing disable wire, the timing goes past the end of the tab.
You need a special timming light to do so. It takes your initial and cam timming and combines them and gives you your total. Also a scanner should give you the same info. Somethin you might try and thats putting your stock chip back in. It cant hurt also what ecm are you using?
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 09-27-2005   #5
george88gta
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Re: engine pings

Quote:
Originally Posted by fearthisgta
You need a special timming light to do so. It takes your initial and cam timming and combines them and gives you your total. Also a scanner should give you the same info. Somethin you might try and thats putting your stock chip back in. It cant hurt also what ecm are you using?
O.K. here is an update. Pcm is a GM factory rebuilt unit, it is about 5 years old. Hooked up the scanner today and went for a ride. Engine warm, idling, total advance is 24 degrees, temp was 190. Knock sensor read zero. Knock retard was zero degrees. From a full stop, accelerating slowly, at about 1300 rpm, engine started to ping and timing was 34 degrees advanced. Continued to accelerate up to 3000 rpm and advance went up to 36 degrees. After 3000 rpm, advance dropped back to 28 degrees and stabilized around 22-24 degrees. Advance remains fairly steady 22-24 degrees when driving normally. Let car sit for about 1/2 hour and then drove it again. Basically the same results, pinging, what I feel is too much timing at a low rpm and only one hit on the knock sensor readout and one instance of the knock retard showing -2 degrees. At first glance, it looks like the knock sensor is not working. Bought a new one and will install tomorrow. I also noticed that the rich/lean scanner readout would switch very quickly and constantly, between rich and lean. The oxygen sensor readout was also changing rapidly, from around 10 to 800 mv, difficult for the scanner to keep up with the changes. Anyone know if this is normal for the oxygen sensor? I know that on a OBDII Firebird, the oxygen sensor reading does not change this fast. Did not change back to the original chip. The original chip is for a 5.0 and the new engine is a 5.7 with lower compression, different cam.
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Old 09-27-2005   #6
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: engine pings

Quote:
Originally Posted by george88gta
O.K. here is an update. Pcm is a GM factory rebuilt unit, it is about 5 years old. Hooked up the scanner today and went for a ride. Engine warm, idling, total advance is 24 degrees, temp was 190. Knock sensor read zero. Knock retard was zero degrees. From a full stop, accelerating slowly, at about 1300 rpm, engine started to ping and timing was 34 degrees advanced. Continued to accelerate up to 3000 rpm and advance went up to 36 degrees. After 3000 rpm, advance dropped back to 28 degrees and stabilized around 22-24 degrees. Advance remains fairly steady 22-24 degrees when driving normally. Let car sit for about 1/2 hour and then drove it again. Basically the same results, pinging, what I feel is too much timing at a low rpm and only one hit on the knock sensor readout and one instance of the knock retard showing -2 degrees. At first glance, it looks like the knock sensor is not working. Bought a new one and will install tomorrow. I also noticed that the rich/lean scanner readout would switch very quickly and constantly, between rich and lean. The oxygen sensor readout was also changing rapidly, from around 10 to 800 mv, difficult for the scanner to keep up with the changes. Anyone know if this is normal for the oxygen sensor? I know that on a OBDII Firebird, the oxygen sensor reading does not change this fast. Did not change back to the original chip. The original chip is for a 5.0 and the new engine is a 5.7 with lower compression, different cam.
Actually I was refering to the svc # on your PCM. I know on mine they did a svc upgrade when it went bad and it was a new #. Unfortunately I dont rember what the old # is,lol. How ever thats one area to check. The other are is your timming going up and down. I am assuming that thats on and off the gas, correct? Also, when the cam was install, where did you set it at, on the zero dot? AND finallly, make sure you r distributor is dropped in on the #1 cyl at TDC. If its one tooth off there is your problem. Good luck. I hope some of this helps.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 09-26-2005   #7
MunsonGTA
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GTA Year: 1987
GTA Engine: Custom
Re: engine pings

i don't think you screwed up by going to the 350 sensors. It might be the tuning in the chip mixed in with the tuning for the fuel pressure and spark. You should run the normal 6 degree timing. To set the fuel pressure this is what I always did. Turn it up 2 psi at a time until when you are driving and you let off the gas, you hear a popping in your exhaust. That means you are burning off excess gas in your exhaust. Once you get to that point, turn it down 2 psi and you should be where you need to be with your fuel pressure. Hypertech chips are junk, get ahold of us at www.lsracingchips.com and we'll do a much better job.
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87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

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Old 09-26-2005   #8
george88gta
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Re: engine pings

Quote:
Originally Posted by MunsonGTA
i don't think you screwed up by going to the 350 sensors. It might be the tuning in the chip mixed in with the tuning for the fuel pressure and spark. You should run the normal 6 degree timing. To set the fuel pressure this is what I always did. Turn it up 2 psi at a time until when you are driving and you let off the gas, you hear a popping in your exhaust. That means you are burning off excess gas in your exhaust. Once you get to that point, turn it down 2 psi and you should be where you need to be with your fuel pressure. Hypertech chips are junk, get ahold of us at www.lsracingchips.com and we'll do a much better job.
This may sound like a dumb question, but the stock fuel pressure range is 42-47 psi. I have had the pressure up to 50 psi with little improvement. Is there a maximum psi to avoid?
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Old 09-26-2005   #9
nblanchard
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Re: engine pings

I would check your base timing for sure... you may need hotter or colder plugs for the different power this engine produces
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Best Track Time is 14.396 @ 95.71MPH

225.5hp @ 4250rpm (at the wheels)
325.8ft-lbs @ 3250rpm (at the wheels)
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Old 09-26-2005   #10
george88gta
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Re: engine pings

Quote:
Originally Posted by nblanchard
I would check your base timing for sure... you may need hotter or colder plugs for the different power this engine produces
Right now the base or initial timing is set to zero degrees. The plugs are the ones that were specified in the crate engine parts list.
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Old 09-26-2005   #11
nblanchard
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Re: engine pings

zero?? oh my god.. there's your problem... set at 6* with the advance wire unplugged
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Best Track Time is 14.396 @ 95.71MPH

225.5hp @ 4250rpm (at the wheels)
325.8ft-lbs @ 3250rpm (at the wheels)
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Old 09-26-2005   #12
george88gta
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Re: engine pings

Quote:
Originally Posted by nblanchard
zero?? oh my god.. there's your problem... set at 6* with the advance wire unplugged
I retarded the timing to zero to see if it made any difference, it really didnt change much. I can reset it back to 6 degrees advanced, but retarded should have lessened the pinging if it was timing ( at least that is what I think). Adjustments were done with the timing connector unplugged ( the tan wire up on the firewall).
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Old 09-26-2005   #13
nblanchard
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Re: engine pings

do you have access to a scanner? If it's pinging, you'd think the knock sensor isn't doing its job
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Best Track Time is 14.396 @ 95.71MPH

225.5hp @ 4250rpm (at the wheels)
325.8ft-lbs @ 3250rpm (at the wheels)
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Old 09-26-2005   #14
george88gta
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Re: engine pings

Quote:
Originally Posted by nblanchard
do you have access to a scanner? If it's pinging, you'd think the knock sensor isn't doing its job
Yes, I can get a scanner. Have to wait until I can get someone to ride with me who can read the scanner in monitor mode.However, the knock sensor was replaced. I am not sure the pinging is heavy enough to trigger the retard circuits.
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Old 09-26-2005   #15
nblanchard
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Re: engine pings

well... thats the sensors job is to pick up knock... if you can hear it with the naked ear.. that sensor should be able topick that up.
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Best Track Time is 14.396 @ 95.71MPH

225.5hp @ 4250rpm (at the wheels)
325.8ft-lbs @ 3250rpm (at the wheels)
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Old 09-27-2005   #16
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Re: engine pings

your knock sensor should not have to go off that often. It's only supposed to activate rarely. Having that many knocks means something is way off. The knock sensor only retards the timing more so if it's constanly going off it's killing your performance cause most likely it'll retard it too far for good performance. If that makes any sense...
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Old 09-28-2005   #17
nblanchard
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Re: engine pings

I would definately double check your distributor alignment, i think fearthisgta hit it right on the nose there
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Best Track Time is 14.396 @ 95.71MPH

225.5hp @ 4250rpm (at the wheels)
325.8ft-lbs @ 3250rpm (at the wheels)
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Old 09-28-2005   #18
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: engine pings

Yeah, the dist is tricky in dropping in.They make it look easy on tv,BUT I personally have never seen one drop in that easy. Usually it takes a few tries. I have had someone else do it in the past b/c I got soooooo fustrated I just walked away b4 I did somethin I would regret later.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 09-28-2005   #19
george88gta
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Re: engine pings

Quote:
Originally Posted by fearthisgta
Yeah, the dist is tricky in dropping in.They make it look easy on tv,BUT I personally have never seen one drop in that easy. Usually it takes a few tries. I have had someone else do it in the past b/c I got soooooo fustrated I just walked away b4 I did somethin I would regret later.
The part number for the PCM is 16198259. It is a remanufactured unit directly from GM, not an aftermarket. Probably not going to get to play with the beast before the weekend. I will check the distributor and update this thread.
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Old 09-28-2005   #20
FearThisGTA
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GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: engine pings

I "THINK" thats the more recent one,"IF" I remeber correctly. So, unles its a defect in the ECM I would rule it out and I dont think it is.
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Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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