M20 Misfire (Please help....)

[sticksdaman]

Fuck that... I refuse to spend that time and money only to end up with another high milage engine with only about 20 more hp. Not really appealing to me, now an s5x on the other hand.

[iamsam]

Fuck that... I refuse to spend that time and money only to end up with another high milage engine with only about 20 more hp. Not really appealing to me, now an s5x on the other hand.

yes, the S is better than the M, but we happen to already have a complete M50 waiting on the engine stand.

[delatlanta1281]

Sounds like a dead spot on the afm.
Check your ignition harness for grounding.
Do his gauges act funny when his blinkers are on or he turns his lights on?

[iamsam]

Sounds like a dead spot on the afm.

already swapped the afm from a working M20 and it did nothing.

[delatlanta1281]

What about the other two questions

[iamsam]

Sounds like a dead spot on the afm.
Check your ignition harness for grounding.
Do his gauges act funny when his blinkers are on or he turns his lights on?

we checked the engine grounds, one on top and one below, what ground are you referring to on the ignition harness?

Gauges don't act funny as far as i know.

Didn't see these other 2 questions, looks like you added them in after i replied to the first one.

[delatlanta1281]

The fuel injection harness (sorry). Also, what about Fuel pump relays? I am trying to wrap my head around you buddy's problem.... so when he is driving it just "bucks" a bit, is it at wot, or is it just cruising? Does it happen all over the rpm range, or only at certian rpms (say 3500 and it bucks then catches up).

[iamsam]

The fuel injection harness (sorry). Also, what about Fuel pump relays? I am trying to wrap my head around you buddy's problem.... so when he is driving it just "bucks" a bit, is it at wot, or is it just cruising? Does it happen all over the rpm range, or only at certian rpms (say 3500 and it bucks then catches up).

where is the ground on the fuel inj harness?

didn't mess with fuel pump relays, it doesn't seem like it is a fuel pump problem... but it could be.... where are the relays?

It doesn't buck at all. What happens is that above a certain throttle load it has a steady miss on one of the cylinders, as in it loses power and makes the "B-d-d-d-d-d-d" sound if you know what i mean.

[delatlanta1281]

After reading the other thread (http://www.r3vlimited.com/board/showthread.php?t=123558)
I have a suggestion. No matter how wierd it may seem, have you replaced the coolant temp sensor? I have a friend that was having issues kind of like this, it would run well, then every once in a while it would miss. It started getting worse and worse until he was able to chase the problem down to the coolant temp sensor. This problem would leave him stranded, bog his motor, give him starting issues, it was weird.

[delatlanta1281]

where is the ground on the fuel inj harness?

didn't mess with fuel pump relays, it doesn't seem like it is a fuel pump problem... but it could be.... where are the relays?

It doesn't buck at all. What happens is that above a certain throttle load it has a steady miss on one of the cylinders, as in it loses power and makes the "B-d-d-d-d-d-d" sound if you know what i mean.

There are no grounds persay, but if there is cracking in the wiring , an injector will fire funny or the harness will ground against the engine.

[iamsam]

hmm... we will definitely check this. And the coolant temp sensor thing is interesting. If they are not expensive it won't hurt to replace it.

[quikveedb2]

After reading the other thread (http://www.r3vlimited.com/board/showthread.php?t=123558)
I have a suggestion. No matter how wierd it may seem, have you replaced the coolant temp sensor? I have a friend that was having issues kind of like this, it would run well, then every once in a while it would miss. It started getting worse and worse until he was able to chase the problem down to the coolant temp sensor. This problem would leave him stranded, bog his motor, give him starting issues, it was weird.

dude, this describes my misfire issues to a "T", i just got my temp sensor in the mail, along with fuel pump relay and cps. i hope it fixes my issue & i can drive to work tonight instead of riding the fixie! iirc the temp sensor affects timing & mixture and so could cause the aforementioned issues.

[iamsam]

dude, this describes my misfire issues to a "T", i just got my temp sensor in the mail, along with fuel pump relay and cps. i hope it fixes my issue & i can drive to work tonight instead of riding the fixie! iirc the temp sensor affects timing & mixture and so could cause the aforementioned issues.

once you install the parts, please update the thread! i want to see if this works for you.

[quikveedb2]

i'm gonna do the temp sensor this afternoon and probably cps tomorrow, i"ll keep you posted.

[sticksdaman]

I recently replaced my coolant and water temp sensors, no dice. I will order a fuel pump relay and take it from there.