Author Topic: engine missing  (Read 3069 times)

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Offline TurboCajun

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engine missing
« on: September 05 2012, 07:47:32 PM »
I put in new spark plugs when i change my turbo, I broke my o2 sensor in the process and put an old one in. then went to a car show about 100 miles round trip, on the way there when the car would go into overdrive and lockup the engine was feeling like it had a miss and it was getting worse during the day, at one point on the way back i went WOT and the boost guage stopped at 15psi and was jumping, and now in park with e-brake on, it will not build more than 5 psi and backfiring, so I pulled the plugs and took a picture, looks like all have carbon . all the number are in line on scan master. could the o2 sensor be bad, or something else.
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #1 on: September 05 2012, 09:48:30 PM »
guess I would start by checking the crank sensor and ohming the coil packs
Steve Wood

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Offline TurboCajun

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Re: engine missing
« Reply #2 on: September 06 2012, 07:36:55 PM »
ok changed the crank sensor, still no change, ohm'ed the coil pack 12.49-12.50 m on all three, this was not removing any wiring does that make a difference.
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #3 on: September 06 2012, 08:29:51 PM »
fuel pressure is normal?
Steve Wood

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A lot of broken parts does not make you a racer; it makes you a slow learner.

Offline TurboCajun

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Re: engine missing
« Reply #4 on: September 06 2012, 08:32:53 PM »
i used my spark tester, at the coil pack 5-2 , 3-6 had a very strong spark 1-4 seemed week but steady, i put the tester at the spark plug(#1) and it was firing with out a miss, i pulled the plug (#1) and it was firing (i cleaned the plugs yesterday and the #1 was already black after only 10min of running, I unplug each injector one at a time and the engine change on each. O2s are at 820-830 blms are right at 128 which leads me to beleive that the o2 sensor is working
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #5 on: September 06 2012, 08:51:08 PM »
besides fuel pressure, what are the maf numbers at idle and at ten psi of boost, if it will get that high

also, do the old disconnect the cam sensor bit again
Steve Wood

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Offline TurboCajun

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Re: engine missing
« Reply #6 on: September 06 2012, 09:05:37 PM »
ok Af at idle is 7, in drive trying to boost when it gets to 0 on the guage it starts to backfire with AF  at 55, I unplugged the cam sensor and was able to get 2psi of boost and no backfire but the motor sounds like its straining really bad and AF at 70. after I let off the gas it sound and felt like its running on three cyl.  Steve I did not check fuel pressure do you think that would cause the problem? if so I will check it tomorrow.
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #7 on: September 06 2012, 09:08:37 PM »
if it is way low, yes

see if it is right at idle, hose off, and if it rises as the vacuum drops toward boost

the maf is a little high if the idle speed is normal
Steve Wood

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Offline TurboCajun

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Re: engine missing
« Reply #8 on: September 06 2012, 09:16:41 PM »
Thanks a bunch Steve, I will check it tomorrow
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #9 on: September 06 2012, 09:49:27 PM »
The interesting thing is that 5&2 are on a common coil  as are 1&4....  those look richer

and 3&6 are also and those two look more normal than the others.

Maybe the module is acting up?  You got another one to try?

Also, if you have another maf, try it...the maf is often around 200 at ten psi according to Eric...but, if we cannot get that much boost, who knows

Steve Wood

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A lot of broken parts does not make you a racer; it makes you a slow learner.

Offline TurboCajun

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Re: engine missing
« Reply #10 on: September 07 2012, 04:51:37 PM »
fuel pressure is normal and rises with boost, maf is at 6 @825 rpm 7@ 900 and rises with acceleration. I also put in another O2 sensor. (nothing changes). I dont have an extra module, I am going to put my old plugs back in just to try.
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline TurboCajun

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Re: engine missing
« Reply #11 on: September 07 2012, 06:30:53 PM »
well here it is -- pulled all the plugs and ran a compression test, all cyl @ 130-135. I put my old plugs back in and at the same time my wife is driving up with the master pro coil pack from oreilly's, I didnt change the coil pack and started the car and the backfiring and missing is gone, went for a ride and all is good, still have a lil rough idle but i also have an exhaust leak, I am not going to fool with it untill my new headers come in. Thanks Steve for your help it is much appreciated. should i return the coil pack are just keep it for a spare
85 GN -- Converted to 87 set-up using 66/72 turbo, front mount I/C, 80lb injectors,gn1 heads 14 bolt 1.65 roller rockers stud mount, ported intake with plate, fuel hot wire, 3" dp, running 24psi., alky kit, stroker 20 over, 212/206 roller,  best time 10.995 @ 121 1.56 60ft

Offline Steve Wood

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Re: engine missing
« Reply #12 on: September 07 2012, 06:44:52 PM »
something fouled those plugs...not sure what...

Return the coil...I suspect I have a better one on the shelf in the garage if problems arise
Steve Wood

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A lot of broken parts does not make you a racer; it makes you a slow learner.

 

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