1990 Turbo 1.6 running rough at high rpm, cuts boost
01-12-2013, 04:09 PM
#1
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1990 Turbo 1.6 running rough at high rpm, cuts boost
So I seem to have a never-ending supply of problems with this car.
Background: I swapped a used 1990 motor into my car with all of my turbo parts that I had previously been using, except with a new much smaller turbo. I've been driving for at least a few hundred miles with no problems, save for an oil leak at my turbo feed line.
Problem: When I push it above even 4k or so, seemingly regardless of the gear, the exhaust changes tones, and the motor seems to struggle to accelerate. Usually when this happens, I get a nice pop out of the exhaust on shifts. It may be boost-dependent, and if it is, it looks to be around 6psi, at which point I no longer build boost. Or at least not at any acceptable rate. Injector duty cycles are around 30-40% at most. The turbo is a .42A/R compressor with a .48 or so turbine I believe. Well matched to this motor. I'm running MiataLink by Link Engine Management, with a built in MAP sensor. Needless to say, there is no POS MAF sensor. My wastegate operates properly as far as I can tell, and it's set at about 8-10 psi.
The problem happened immediately after at some point on a cold start I decided to push it near my rev limiter. Which is low, 6200 or so. But it was right after I started it up, and I wasn't really thinking. I still get strong pulls on low end, until that particular point when it just changes. Kind of like a reverse VTEC. Up until then, great turbo spool, great power, then nothing.
I have tried to watch my AFRs on my wideband, but I get nervous pushing it into that section, and haven't really gotten any definitive results there. I am running slightly rich on idle and cruise, as well as in acceleration from slight vacuum through low boost ranges.
Background: I swapped a used 1990 motor into my car with all of my turbo parts that I had previously been using, except with a new much smaller turbo. I've been driving for at least a few hundred miles with no problems, save for an oil leak at my turbo feed line.
Problem: When I push it above even 4k or so, seemingly regardless of the gear, the exhaust changes tones, and the motor seems to struggle to accelerate. Usually when this happens, I get a nice pop out of the exhaust on shifts. It may be boost-dependent, and if it is, it looks to be around 6psi, at which point I no longer build boost. Or at least not at any acceptable rate. Injector duty cycles are around 30-40% at most. The turbo is a .42A/R compressor with a .48 or so turbine I believe. Well matched to this motor. I'm running MiataLink by Link Engine Management, with a built in MAP sensor. Needless to say, there is no POS MAF sensor. My wastegate operates properly as far as I can tell, and it's set at about 8-10 psi.
The problem happened immediately after at some point on a cold start I decided to push it near my rev limiter. Which is low, 6200 or so. But it was right after I started it up, and I wasn't really thinking. I still get strong pulls on low end, until that particular point when it just changes. Kind of like a reverse VTEC. Up until then, great turbo spool, great power, then nothing.
I have tried to watch my AFRs on my wideband, but I get nervous pushing it into that section, and haven't really gotten any definitive results there. I am running slightly rich on idle and cruise, as well as in acceleration from slight vacuum through low boost ranges.
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01-12-2013, 06:43 PM
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Not sure if it matters, but I have really nice throttle response and lots of low-end torque right now, it's just high rpms that bog.
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01-14-2013, 09:27 AM
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Yeah I did. It's much better, but still likes to cut out around 5500. I also fixed an exhaust leak before the turbo as well, and its quicker but still not right. I put in stock heat range coppers because that's all that was available to me. I'm ordering some 1-2 step colder iridiums soon.
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01-15-2013, 01:51 PM
#8
Yeah I did. It's much better, but still likes to cut out around 5500. I also fixed an exhaust leak before the turbo as well, and its quicker but still not right. I put in stock heat range coppers because that's all that was available to me. I'm ordering some 1-2 step colder iridiums soon.
Colder plugs, and a smaller gap. Hmmm, I *think* I am at 0.030 with BKR7E's, or possibly 0.033. I will have to check my notes. Running 6psi with JRSC. No misfires.
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01-15-2013, 02:10 PM
#11
Didn't mean to doubt you, Brain. I misread you.
Perhaps you meant "stick" instead of "still"?
Otherwise I wouldn't have brought up the colder plugs. I didn't know the 90-93 plugs were already colder. Perhaps it is on 'other' forums that the BRR7E's were recommended for FI setup's.
The consensus would be that stock heat range for 90-93 (6) should be good, and that a misfire sounds like tuning, gap, or needing COP's?
Perhaps you meant "stick" instead of "still"?
Otherwise I wouldn't have brought up the colder plugs. I didn't know the 90-93 plugs were already colder. Perhaps it is on 'other' forums that the BRR7E's were recommended for FI setup's.
The consensus would be that stock heat range for 90-93 (6) should be good, and that a misfire sounds like tuning, gap, or needing COP's?
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01-15-2013, 02:56 PM
#12
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1) new plugs, .30 gap.
2) check your tuning, make some logs, make sure you aren't hitting boost cut or something stupid, make sure the AFR's are good and timing is safe and it's not detonating.
3) if its still doing this, fix your ignition system. you could waste money on new plug wires and a coil, or you could be a man and read the COP thread and do it on the cheap. It cost me about 150 bucks, and I bought brand new coils, brand new pigtails, etc. You could certainly do the COP mod for about 75 bucks if you go for used cops w/ pigtails.
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01-17-2013, 05:38 PM
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Steps I would take.
1) new plugs, .30 gap.
2) check your tuning, make some logs, make sure you aren't hitting boost cut or something stupid, make sure the AFR's are good and timing is safe and it's not detonating.
3) if its still doing this, fix your ignition system. you could waste money on new plug wires and a coil, or you could be a man and read the COP thread and do it on the cheap. It cost me about 150 bucks, and I bought brand new coils, brand new pigtails, etc. You could certainly do the COP mod for about 75 bucks if you go for used cops w/ pigtails.
1) new plugs, .30 gap.
2) check your tuning, make some logs, make sure you aren't hitting boost cut or something stupid, make sure the AFR's are good and timing is safe and it's not detonating.
3) if its still doing this, fix your ignition system. you could waste money on new plug wires and a coil, or you could be a man and read the COP thread and do it on the cheap. It cost me about 150 bucks, and I bought brand new coils, brand new pigtails, etc. You could certainly do the COP mod for about 75 bucks if you go for used cops w/ pigtails.
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01-17-2013, 06:06 PM
#14
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That said, stfu
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