1993 Runs rough H15 H16 H31
10-08-2018, 10:55 AM
#1
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1993 Runs rough H15 H16 H31
Hey guys/gals,
I have a 1993 40th anniversary vette that has gradually started running rough like it's missing through all RPMs. The check engine light is intermittent and doesn't read anything at the auto parts store. The dash throws the codes H15, H16 and H31. I am not sure where to go next for diagnostics. Is this a slam dunk opti spark or what else should I check? Thanks for the help!!!
I have a 1993 40th anniversary vette that has gradually started running rough like it's missing through all RPMs. The check engine light is intermittent and doesn't read anything at the auto parts store. The dash throws the codes H15, H16 and H31. I am not sure where to go next for diagnostics. Is this a slam dunk opti spark or what else should I check? Thanks for the help!!!
10-09-2018, 08:48 AM
#3
Le Mans Master
It's very unlike that's an opti problem. Start with some diagnostic questions and checks:
- Does it do this equally as badly when cold vs warmed up?
- Does it feel like one cylinder consistently not firing, or a random misfire?
- Test each plug for spark.
- Check fuel pressure and check each injector for signal with a noid light.
- Get some data logging info to see where your A/F ratios and timing are.
10-09-2018, 09:22 AM
#4
If you're actually experiencing H15 & H16 for a '93 I'd think you look towards ETC (DTC 15) issues and correct that 1st maybe. For a '93 I don't believe there's actually a DTC 31.
Post#3 mentions very appropriate diagnostics. H - of course is HISTORY.
Do you have the FSM for DTC diagnostics?
Post#3 mentions very appropriate diagnostics. H - of course is HISTORY.
Do you have the FSM for DTC diagnostics?
Last edited by WVZR-1; 10-09-2018 at 09:27 AM.
10-13-2018, 01:21 PM
#5
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Thanks for the info!!!! I do not have an FSM unfortunately.
it seems to be a regular miss at all temps. I am about to check the fuel injectors. I have new spark plugs with good consistent spark. But now it is idling high. I had this problem in the past and fixed it with a new TPS.
I am not sure how to get air fuel ratios.
thanks again for all the help
it seems to be a regular miss at all temps. I am about to check the fuel injectors. I have new spark plugs with good consistent spark. But now it is idling high. I had this problem in the past and fixed it with a new TPS.
I am not sure how to get air fuel ratios.
thanks again for all the help
10-14-2018, 08:55 PM
#6
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I adjusted my TPS to .54v and idle is fixed. I cleaned out my fuel injectors with engine degreaser and it runs smooth now (one was really clogged up).... well most of the time it runs smooth... my fuel pressure was 10psi at engine off key on, it is low 30s at idle and low 40s with increased throttle.
New symptoms: occasionally sputters during acceleration above 2500rpms. It still has H16 for opti spark and now has H64 for right bank lean O2.
is this a fuel pressure issue vs fuel injector issue or is it really the opti spark ruining my day? Or is it TPS still? Thanks
New symptoms: occasionally sputters during acceleration above 2500rpms. It still has H16 for opti spark and now has H64 for right bank lean O2.
is this a fuel pressure issue vs fuel injector issue or is it really the opti spark ruining my day? Or is it TPS still? Thanks
10-15-2018, 07:35 AM
#7
Safety Car
Original opti? Change it! Maybe just the rotor and cap Use marine grade RTV around OPTI to seal.after you assemble it. Should take a day to repair if Harmonic Balancer comes off easily. Use a lot of PB Blaster and let soak . Keep Blaster away from spark plug wires it might break down insulation on jacket. At least you received those history codes for reference.