My car has a misfire and detonates

[Synned]

Okay, I assume these two problems are related, probably from a lean condition. The car misfires around idle to 1700rpms it vibrates badly and surges. On the highway it pings (only on highway because im running 93 with octane booster).

The MAF is cleaned.
Pulled codes and got ECT sensor out of testing range. (Could this be it?! Its a new sensor from a for dealer about 4 months ago maybe just a bad one)

Passed the cylinder balance test.
Plugs, wires, and cap and rotor are under 4 months old. New o2's.

Does this sound like something EGR related? Or just maybe that ECT causing a lean condition and causing my lean misfire and detonation.

Is a lean misfire not really a spark problem? What is a lean misfire?
It only happens near idle, I would guess a spark problem happens all the time.

 

[Synned]

ttt

 

[Synned]

If the plug wires are crossed, could this cause a misfire?

I'm going ot buy some wire looms tomorrow, want to know if itll help the misfiring.

 

[Rynb15]

If the plug wires are crossed, could this cause a misfire?

it would run like crap

 

[HISSIN50]

The ECT can be ohmed out (Jrichker has posted values at various temps). If it is out of calibration (i.e. telling the puter that your motor is warm when it is cold) that can cause issues.

You can do some quick testing on the EGR to make sure that is not it. If you remove the vac line to it at idle, does the idle improve (it should NOT - EGR should not be flowing at idle. Carbon in the seat can hang it up).

If you apply 5-6" hg of vac to the vac nipple on the EGR, note if the diaphram moves. If you do this with the car idling, the car should stumble or die.
Once again, Jrichker has the master list of diagnostics for the EGR.

Do check for cross wires, etc.

Good luck.

 

[Synned]

Sorry for the confusion, I didn't mean "crosses wires" like the wrong spots on the distributer. What I meant was that the wires go over and under each other. Can this cause interference? Let me show you...

 

[HISSIN50]

Sheesh, dial-up about croaked on that one.

You can do the 'spray the wires down with water at night' test and see if you see cross-sparking.

Separated is best, but I have had wires crossing eachother before and as long as the wire is in decent shape, I noted no issues or cross firing.

MHO.
Good luck.

 

[Synned]

Okay, thanks hissin i'm going to try that tomorrow.

I'm also gonna get a cheap pep boys ECT sensor and see if that code goes away...along with the pinging.

Is there a difference between a lean misfire, I mean is it the same thing as a misfire (absense of spark)

 

[Synned]

Okay well the ECT sensor did nothing for me.

I was wondering, if the PCV valve has not been changed in a while, it could be related to detonation right?

 

[HISSIN50]

Synned, I really think the pinging in OD is due to the Low RPM and high load if you try to accelerate much at all. If there was an EGR issue (it was not introducing as much gasses as it should) that could also cause an issue.

PCV really has nothing directly to do with detonation.

Good luck.

 

[Synned]

Okay, so your leaning towards the EGR. I just thought of the PCV maybe letting in oil and that causing the detonation, or maybe a vaccum leak but I guess it can't cause a vacuum leak.
I'll try to go through haynes to see if i can test the EGR.
Thanks

 

[Zero_chance]

Keep in mind that if you pull codes when the engine isnt up to normal op temp, youll get a code for ECT being out of self test range.

 

[Strype]

Just for thought, mine did sorta what you are describing and it was fuel pressure waaay too high... we changed the vacuum hose earlier to the fp regulator which gave it more guess.

 

[Synned]

I dunno guys, this is getting really bad and I don't know what to do. After driving a little it gets worse and worse. I'm going to try a new MAF, anyone have a stocker I could buy?

 

[352Ford2]

Start from the basics, people like to skip steps and then they can't find whats wrong get sent in wrong directions and spend money on useless parts

Read the plugs (do a plug run if you have too), just like your old carbd hot rod, they are your window into the engine.

check and make sure the new parts you put on are right (plugs arn't to hot etc)

if it looks fuel related: Check your fuel pressure

If it looks timing related: check timing

and on and on and on, just go through ALL the steps


DON'T JUST THROW PARTS AT IT, THATS A WASTE OF MONEY AND YOU LEARN NOTHING.

also that is what seperates us from the imports, they are part swapers

 

[HISSIN50]

352, have you had luck reading EFI plugs? Even after a plug (WOT/instant shut down) run, I think the nature of EFI prevents the reading from being as informative as on a carbed set-up.
I do agree that going over what has already been done can double-check things, as well as solidify in your mind what might be likely.

Synned, did activating the BOO switch to unlock the converter ever help with the freeway/OD issue?

Good luck.

 

[Synned]

352, have you had luck reading EFI plugs? Even after a plug (WOT/instant shut down) run, I think the nature of EFI prevents the reading from being as informative as on a carbed set-up.
I do agree that going over what has already been done can double-check things, as well as solidify in your mind what might be likely.

Synned, did activating the BOO switch to unlock the converter ever help with the freeway/OD issue?

Good luck.

Do you mean the problem where when im driving the converter tries to lock up and it feels like im driving over those small bumps that stop you from going to sleep on the highway?
Actually yeah, when I hit the brake it stops the converter from trying to lock up. It still feels bad between moderate shifts, like studders and it still does that lock up thing from time to time but yeah im pretty sure its the converter because if i tap the brakes it stops.

 

[HISSIN50]

Do you mean the problem where when im driving the converter tries to lock up and it feels like im driving over those small bumps that stop you from going to sleep on the highway?
Actually yeah, when I hit the brake it stops the converter from trying to lock up. It still feels bad between moderate shifts, like studders and it still does that lock up thing from time to time but yeah im pretty sure its the converter because if i tap the brakes it stops.

The small bumps feeling is likely a calibration issue. A switch to MV has helped some.

Actually, unlocking the converter helps unbog the motor. So if you are cruising along and it starts to ping (like if the freeway has a slight upward grade), activating the BOO switch will help unbog the converter, get the revs up and might let you cruise along w/o pinging (till the converter locks up again).

Just be real careful of people behind you, if you are activating the BOO by pressing the brake lights.

The 5 spd folks can have the same sort of issue with numerically low gears (2.73, etc) if in 5th at 1100 RPM, for instance. In that case, it is just a lack of gearing for a given load.

 

[352Ford2]

352, have you had luck reading EFI plugs? Even after a plug (WOT/instant shut down) run, I think the nature of EFI prevents the reading from being as informative as on a carbed set-up.
I do agree that going over what has already been done can double-check things, as well as solidify in your mind what might be likely.

Synned, did activating the BOO switch to unlock the converter ever help with the freeway/OD issue?

Good luck.

I do have good luck at least expecialy when they are running that bad. EFI will still show up the timing mark on the ground strap, but the Air fuel is a little more difficult to see. I highly recomend one of those spark plug inspector magnifying glasses things, it really helps expecialy we really trying to nail down a tune.