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96 C4 - Backfire Through Manifold - Opti / Crankshaft Position Sensor
Last couple of months - some slight hesitations while driving. Then RPM gage foes to zero while driving but the car is running. Some bucking. Got to work, started it up after work, bucking, ASR shuts off. Limp it home.
- Crankshaft Position Sensor - I find that it's broken. So I get a replacement.SU1071 from Autozone. Installed it. It looks nothing like the DR6237. I ended up pulling it and I found the Dr6237 so I know that that installed.
But everywhere on the internet says it is. Nothing is resolved. I do find a direct replacement on ebay. Does not seem to be a direct replacement for DR6237
Getting a lot of backfire through the manifold - Scan tool now says P0372. Hi Res Opti spark..... I have an MSD optispark on the car that is about 2yrs old and not even 10K miles. I called MSD - they say $30 to $130 to repair it. So I guess it's worth removing from the car and sending in for repair.
Does anyone know if the Suggested replacement CPS actually works as a replacement?
Trying to figure out what to do with the MSD opti. I guess return it and see if there is an issue. Wonder if there is anything else to trouble shoot.
Last couple of months - some slight hesitations while driving. Then RPM gage foes to zero while driving but the car is running. Some bucking. Got to work, started it up after work, bucking, ASR shuts off. Limp it home.
- Crankshaft Position Sensor - I find that it's broken. So I get a replacement.SU1071 from Autozone. Installed it. It looks nothing like the DR6237. I ended up pulling it and I found the Dr6237 so I know that that installed.
But everywhere on the internet says it is. Nothing is resolved. I do find a direct replacement on ebay. Does not seem to be a direct replacement for DR6237
Getting a lot of backfire through the manifold - Scan tool now says P0372. Hi Res Opti spark..... I have an MSD optispark on the car that is about 2yrs old and not even 10K miles. I called MSD - they say $30 to $130 to repair it. So I guess it's worth removing from the car and sending in for repair.
Does anyone know if the Suggested replacement CPS actually works as a replacement?
Trying to figure out what to do with the MSD opti. I guess return it and see if there is an issue. Wonder if there is anything else to trouble shoot.
The crankshaft position sensor will not cause backfire through the intake manifold. It only tells the PCM if the engine is grossly misfiring. Think of it as a monitor only. The engine can still run normal if it goes bad.
But your MSD Optispark sounds like it is bad for sure.
If you read any of the posts on this forum the MSD Opti is problematic at best.
I almost bought one but ended up buying a Petris rebuilt Optispark instead.
So just a quick lesson for you; the original, no longer available new Mitsubishi Optical Sensor is the best. Even used ones last longer than the new garbage Chinese replacements.
If you have your original Optispark that has the Mitsubishi Optical Sensor in it have that rebuilt instead.
If you can't do it yourself then there is a guy on eBay that will.
Otherwise go with the Petris Optispark.
The crankshaft position sensor will not cause backfire through the intake manifold. It only tells the PCM if the engine is grossly misfiring. Think of it as a monitor only. The engine can still run normal if it goes bad.
But your MSD Optispark sounds like it is bad for sure.
If you read any of the posts on this forum the MSD Opti is problematic at best.
I almost bought one but ended up buying a Petris rebuilt Optispark instead.
So just a quick lesson for you; the original, no longer available new Mitsubishi Optical Sensor is the best. Even used ones last longer than the new garbage Chinese replacements.
If you have your original Optispark that has the Mitsubishi Optical Sensor in it have that rebuilt instead.
If you can't do it yourself then there is a guy on eBay that will. Otherwise go with the Petris Optispark.
That was my choice. I am satisfied. Had three others before, one MSD, that crapped out soon after installation.
BTW, just replaced my CPS a couple of months ago. Car was hitting a really hard lick and stopped while trying to start. New CPS, delco, has cured it. To install, you can get clearance by loosening motor mount bolts until only two threads are holding. Gently jack up engine until nuts engage (watch top of engine for firewall clearance. This gives you just a little more room to get to sensor from underneath but it works.
Last edited by SouthernSon; Jul 14, 2021 at 06:26 PM.
Update - went the cheaper route for now and sent the $650 MSD optispark back for service - they rebuilt and replaced with an upgraded 2019 sensor design (REBUILD AND SHIPPING/INSURANCE $200). It returned and I waited for water pump and plug wires and cooler weather. Just installed the opti and watched for the key alignment feature to get the key alignment correct. and before putting the water pump on the bellows (MAF) I tried to start it up and it still is having a problem. (checked wires - everything connected in proper sequence). new module. Checked coil and it sparks out. still popping through manifold.
Took the valve cover off and found teh rocker arm stud broken in Cyl 6. Pulled head - repaired and put back together. Optispark was one issue, broken exhaust valve rocker arm was the other.
96 C4 - Backfire Through Manifold - Opti / Crankshaft Position Sensor
