What is this?

Joined
11 July 2005
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449
Location
Landenberg, PA
Unsure.jpg


It is located behind the passenger seat in the engine compartment.
Below is a picture of it from farther away.

Top_ignitor_1_.jpg


It looks exactly like an ignitor that I replaced here:

Top_ignitor_2_.jpg
 
When you have the part number (pictured), it's easy to look up a part on parts websites like Tim's.

37950-PR7-A31 - DETECTION UNIT, MISFIRE - List Price $699.03
 
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Not only that - I have a feeling this part may be the source of the mysterious misfire codes that have plagued some of us...

This is only on OBDII cars.
 
Not only that - I have a feeling this part may be the source of the mysterious misfire codes that have plagued some of us...

This is only on OBDII cars.

Well we can only hope, but we have yet to confirm that :tongue: (it's Cam)
 
What the hell is a detection unit for misfires? :confused: I mean doesn't the ECU already detect that or is this the newer fancier OBDII means of doing so? :rolleyes: Curious people want to know. :biggrin:

Al
 
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Not only that - I have a feeling this part may be the source of the mysterious misfire codes that have plagued some of us...

This is only on OBDII cars.
Yes i suspected that right away as i don't recall seeing that lately, we mostly have OBD-I cars here.
 
I really hope this part is the cause for all my frustration lately.

My X (1995) has been giving me all sorts of mysterious misfire codes and Angus and I are a bit stumped. The car is not actually misfiring, the engine is running smooth. I have not started a troubleshooting thread on prime yet but I'm close. After replacing plugs/coils/ignitor, getting injectors cleaned/tested, draining fuel and putting fresh 94 in, no change (albeit the car does run noticeably smoother with all these new parts). It throws 1201-1203 + 1300 (all at once) right away upon driving and then 1204-1206 later (individually). It will constantly throw misfire codes cruising on the highway between 2-3k rpm under light load, yet it's not ACTUALLY misfiring.

I'm looking to borrow someones MDU to see if this is the part that is plaguing me with this dreaded CEL light. It's getting quite frustrating :mad:
 
Yep, been there, done that. That Misfire Detection Module, if not tight connections, can cause arcing that will fry your engine harness. Look at the the bare wires on the harness feeding the injectors on the rear bank. If they are brittle, you will need to replace the engine harness. Ask me how I know....

Good luck and let us know how things end.
 
Well the second one is an alternator, and the third one's a throttle body. Not sure of the first ;)
 
I figured I should update this thread for anyone having a similar issue.

After having a different mechanic look at my car, it turns out the solution to my random misfire codes was a simple valve adjustment. After a valve adjustment, the misfire codes disappeared! I certainly went through a lot of headache to get to that solution, so hopefully someone else can benefit from this post.
 
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