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marshall_mosty
01-19-2009, 01:13 PM
Guys,
Took the car to the track yesterday and it ran well except it seemed to be stumbling a bit climbing through the RPM band. Nothing to fall on its face, but enough to hear/feel from the driver's seat.

Today, Michael and MFW took my car to the dyno and they didn't get the car above 5K due to the horrible popping/missfire.

I changed the plugs/cap/rotor and bad wire since the last enduro.

Car still put down 288HP/315TQ with stopping at 5K, so I'm sure it would be around 310HP or so.

The miss didn't seem to hurt the power, but did make the dyno graph look a bit funny.


What would be the first thing to look at? Apparently the car ran fine from 2K to 4K and then started to fall apart (graph wise).

mitchntx
01-19-2009, 01:42 PM
Guys,
Took the car to the track yesterday and it ran well except it seemed to be stumbling a bit climbing through the RPM band. Nothing to fall on its face, but enough to hear/feel from the driver's seat.

Today, Michael and MFW took my car to the dyno and they didn't get the car above 5K due to the horrible popping/missfire.

I changed the plugs/cap/rotor and bad wire since the last enduro.

Car still put down 288HP/315TQ with stopping at 5K, so I'm sure it would be around 310HP or so.

The miss didn't seem to hurt the power, but did make the dyno graph look a bit funny.


What would be the first thing to look at? Apparently the car ran fine from 2K to 4K and then started to fall apart (graph wise).

Sounds like an opti-spark is dying. 8)

AllZWay
01-19-2009, 02:03 PM
Sounds like an opti-spark is dying. 8)

http://www.smittysspeedshop.com/smilies/opti.gif

But I am thinking that is probably not his problem...although I don't know much about Fords. :P

evarner
01-19-2009, 02:08 PM
TFI module? During the popping and misfire, was the tach bouncing needle bouncing around?

Mass Air car? Could always check the 2nd filament wire on the meter (if you can see it) for any debris.

Fuel Pressure was steady and didn't drop off approaching 5k?

Reset the computer by disconnecting battery and leaving the ignition on "run" for about 5-10min. Connect battery and then start the car - leaving it run without touching the throttle for 10min (fast EEC learn).

I've had to do at least one of the above on my drag cars when they had the same symptoms as what you described.

.02

marshall_mosty
01-19-2009, 02:14 PM
TFI module? During the popping and misfire, was the tach bouncing needle bouncing around?No, tach is stable.


Mass Air car? Could always check the 2nd filament wire on the meter (if you can see it) for any debris.I'll check that.


Fuel Pressure was steady and didn't drop off approaching 5k?Don't know. Didn't have a guage hooked up at that point.


Reset the computer by disconnecting battery and leaving the ignition on "run" for about 5-10min. Connect battery and then start the car - leaving it run without touching the throttle for 10min (fast EEC learn).
Don't know if this one will work since I just have the master disconnect, toggle switch for the EFI system, and the starter button. The one toggle powers the EFI and the fuel pump.

One thing I will look at is the fuel pump/strainer. Since I've had lots of issues with this in the past, it might have been fuel starving at high RPM if the strainer fell off or is plugged.

Rob Liebbe
01-19-2009, 03:25 PM
Make sure the battery voltage is good and the alternator is charging. I recently had a similar problem on another Mustang. He changed the fuel pump and got resolution.

AI#97
01-19-2009, 05:02 PM
we hooked up a fuel pressure guage...FP was steady at 40 at idle and held firm at 48 during the pull and never waivered. I am guessing a bad coil or some sort of valve problem from the enduro.

For reference from the first pull. a/f was in the low 11's and dipped to 10.8 once. We pulled plugs and they weren't fouled. I backed the FPR out 1/4 turn and the a/f was better on the second pull in the low 12's high 11's but steady at 12.2 during the pull. started breaking up at 4200, bad at 4500-4600 and we killed the pull at 4800.

I was perplexed and we swapped the modules with a spare from micheals pit box. Car cranked perfectly every time and didn't sound weak...but the bendix was a cranky when we put it on the trailer...but still cranked strong. I ran out of knowledge at that point and the dyno operator was actually the previous shop owner of Modern Mustang Performance and even he was scratching his head. Great guy too who was interested in CMC!!!!

Oh, and 1 chambers are f'n loud!!! LOL! :lol:

Rob Liebbe
01-19-2009, 08:54 PM
I'm still going with low voltage. Easy to check.

Todd Covini
01-19-2009, 09:16 PM
I'm going to go with Throttle Position Sensor (TPS) for $100, Alex.
http://www.celebritywonder.com/wp/Jeopardy_TV_Walpaper_1_800.jpg

AI#97
01-19-2009, 09:20 PM
I'm going to go with Throttle Position Sensor (TPS) for $100, Alex.

You know, that is one thing we didn't check but could be checked with a volt meter in about 30 seconds. are the 5.0's 1-5v with wide open being about 4.8v..? and closed being 1.0v? Pretty normal for most cars I think.

Marshal, the more I think about it I am coming down to no alt output or bad coil. If it were doing what it did today on Sunday, you would have brought the car in which tells me its something that is getting slightly worse...my money is on alternator at this point.

I do hope you figure it out though and it's great to sort it now instead of at the track!!!! Good luck!

marshall_mosty
01-19-2009, 09:37 PM
Well, here's my course of action this weekend (If Michael can't figure it out before then).

1. Pull codes
2. Change TPS (.98 volts closed)
3. Change Coil
4. Change Distributor
5. Change TFI
6. Change Fuel Pump and strainer
7. Check alternator output


I just want it to be rock solid for the enduro. Is that too much to ask? :?

Todd Covini
01-19-2009, 10:19 PM
If you want it rock solid for the enduro, you'll need Liebbe & I on your team. Otherwise, go thru your little checklist and hope for the best. :D

GlennCMC70
01-19-2009, 10:26 PM
If you want it rock solid for the enduro, you'll need Liebbe & I on your team. Otherwise, go thru your little checklist and hope for the best. :D

that very same checklist put you guys how many laps down? 4? 5? more?

jeffburch
01-19-2009, 10:32 PM
VatoZone can check the alt.

jb

RichardP
01-19-2009, 10:47 PM
You might want to try a different brand of distributor cap. I had the same issue a few years back. I swapped caps from my wife's street car. Problem still there and the problem didn't show up on my wife's car. Caps were both from autozone. Ford cap fixed it (after swapping a staggering list of other parts with no effect).

Good luck.


Richard P.

marshall_mosty
01-20-2009, 05:57 AM
Richard,
I'll go and source a OEM ford cap and rotor to test as well.

donovan
01-20-2009, 09:50 AM
Could something be setting of the stock rev limiter or a aftermarket limiter... I had a similar problem after a transmission swap last season. Unplugged the speed sensor and problem went away.

I could rev the engine to 6500 while parked... it would only stumble when moving in a gear... the car is loud and with my helmet on I did not realize it was the stock rev limiter.

DD

AI#97
01-20-2009, 11:25 AM
Could something be setting of the stock rev limiter or a aftermarket limiter... I had a similar problem after a transmission swap last season. Unplugged the speed sensor and problem went away.

I could rev the engine to 6500 while parked... it would only stumble when moving in a gear... the car is loud and with my helmet on I did not realize it was the stock rev limiter.

DD

It would still gain rpm...just really rough and missing.

David Love AI27
01-20-2009, 11:35 AM
Could something be setting of the stock rev limiter or a aftermarket limiter... I had a similar problem after a transmission swap last season. Unplugged the speed sensor and problem went away.

I could rev the engine to 6500 while parked... it would only stumble when moving in a gear... the car is loud and with my helmet on I did not realize it was the stock rev limiter.

DD

My car stumbles at @ 5200 for some reason and it feels like the limiter, I have a 6000 chip in it (motor never gets there) because I don't have the 5000 series chips. Could my limiter be messing up? how would I check it... it is a MSD with MSD dist..

jeffburch
01-20-2009, 11:40 AM
DL, look at the MSD rotor.

jb

Rob Liebbe
01-20-2009, 02:30 PM
DL - listening to your car on the dyno and looking at the sheets, I don't think it is rev limiter. The engine still made it to 6000 rpm, it abruptly stopped making power after 5000 rpm. Definitely something wrong there. Until you get it fixed, there is no reason for you to shift at anything higher than 5000 rpm.

AI#97
01-20-2009, 03:31 PM
Possible that the MAF is pegging with the cold weather?

My understanding of the EEC, and I could be wrong is that the MAF only plays a part in the a/f at part throttle, and the o2's handle a/f at WOT...?

Maybe that is just with my EECV...

BlueFirePony
01-20-2009, 03:53 PM
Possible that the MAF is pegging with the cold weather?

My understanding of the EEC, and I could be wrong is that the MAF only plays a part in the a/f at part throttle, and the o2's handle a/f at WOT...?

Maybe that is just with my EECV...
Some stock MAFs can peg at high air flow. I know the S197 (and the '04 lighting too?) have issues at high flow. I am pretty sure (at least my tuning shows) that the S197 MAF plays a part at full throttle though.

marshall_mosty
01-20-2009, 04:47 PM
My understanding of the EEC, and I could be wrong is that the MAF only plays a part in the a/f at part throttle, and the o2's handle a/f at WOT...?I'll need to dig out my EEC-IV strategy guide and see what WOT looks at sensor wise.

AI#97
01-20-2009, 05:26 PM
My understanding of the EEC, and I could be wrong is that the MAF only plays a part in the a/f at part throttle, and the o2's handle a/f at WOT...?I'll need to dig out my EEC-IV strategy guide and see what WOT looks at sensor wise.

You might look at a new intake hose too! if the wires in that hose are loose, it could collapse and choke the motor...ie sucking shut!

I will say this much though, you are likely making more power than you ever thought! the numbers looked good until that started happening! 8)

David Love AI27
01-20-2009, 05:46 PM
DL, look at the MSD rotor.

jb

Changed cap and rotor the morning of dyno run... center button on old rotor was worn out and cap was full of the old material, I'm assuming it is carbon... sprayed out dist with elec cleaner...

jeffburch
01-20-2009, 07:17 PM
DL, look at the MSD rotor.

jb

Changed cap and rotor the morning of dyno run... center button on old rotor was worn out and cap was full of the old material, I'm assuming it is carbon... sprayed out dist with elec cleaner...


Hmmm, keep an eye under there. I've heard of msd rotors/caps not lasting a weekend.

jb

cobra132
01-21-2009, 01:05 PM
Has the car been sitting for a while, is the fuel fresh??

michaelmosty
01-21-2009, 01:13 PM
Been sitting since the Enduro. I think Marshall ran 3 sessions on Sunday so it should have cycled out all of the gas. I would doubt that 9-month old fuel would be bad??

marshall_mosty
01-21-2009, 02:56 PM
Car basically was out of gas prior to the enduro. Actually ran out of gas putting it on the trailer. Put one gallon of fresh 87 octane and then put 5 gallons of 93 at the track. Two more 5-gallon 93 octane fills during the day as well.

What was left was WELL dilluted prior to the dyno run.

marshall_mosty
01-21-2009, 02:57 PM
I will say this much though, you are likely making more power than you ever thought! the numbers looked good until that started happening! 8)Not bad for a junkyard shortblock still running stock, standard bore, OEM pistons... 8)

David Love AI27
01-22-2009, 09:03 AM
Been sitting since the Enduro. I think Marshall ran 3 sessions on Sunday so it should have cycled out all of the gas. I would doubt that 9-month old fuel would be bad??

word of warning.. the new "blended" fuel seperates... I talked to a boat mechanic last year and he was very busy last summer working on carbs and motors that were messed up due to fuel seperation..

I know this is not the case here, it is just a reminder...

evarner
01-22-2009, 09:53 AM
Out of curiosity, what's the sparkplug gap set at?

michaelmosty
01-22-2009, 10:25 AM
Out of curiosity, what's the sparkplug gap set at?
Good question, I'll check it out tonight.
What should it be on an al. head?

marshall_mosty
01-22-2009, 11:52 AM
I'm pretty sure I had them at .045

BryanL
01-22-2009, 08:01 PM
Been sitting since the Enduro. I think Marshall ran 3 sessions on Sunday so it should have cycled out all of the gas. I would doubt that 9-month old fuel would be bad??

word of warning.. the new "blended" fuel seperates... I talked to a boat mechanic last year and he was very busy last summer working on carbs and motors that were messed up due to fuel seperation..

I know this is not the case here, it is just a reminder...

DL is right on about this. The issue is the ethanol in the gas. If it sits it will end up gumming up the carb and fuel lines. The big problem in boats is that it can actually eat away at the inside of the gas tanks made out of fiberglass and ruin an engine. Lot of mid 80's boats are having this issue right now.

jeffburch
01-22-2009, 08:26 PM
this is exactly why I have my fuel pump wired the way I do.
I open the port on the rail and dump my gas after the event.
The wifes jap POS loves it 8)
jb

marshall_mosty
01-25-2009, 08:25 PM
Okay guys... hopefully I found the problem.

1. Code 51: ECT (Engine Coolant Temperature) sensor was showing high voltage.

2. Spark plugs were gapped at .045 instead of .059. I don't see that being a big deal, but I regapped them anyway.

For my peace of mind, I also changed the IAT (Intake Air Temperature) sensor as well and the ignition coil.

Hopefully will get it to the dyno in the next week or so to make sure it's doing what it should.



Something I found in my files (www.fordfuelinjection.com) talks about failure modes.


"Failure mode is a stand in strategy in the EEC designed to maintain vehicle operation should one or more sensor inputs fail. When a sensor input is perceived to be out-of-limits by the EEC, memorized data from the compters KAM (keep alive memory) will be initiated. EEC continually checks the sensors against its records of normal readings during operating conditions similar to its current state. Randomly the EEC looks at the past to see if the engine is somewhat where it usually is. If for some unknown reason a sensor is off the charts, it can't be trusted. So instead of tuning the engine to a possible faulty sensor reading and harming the engine and driveability, the EEC replaces the sensor reading with the best guess from a past memory. This is why unplugging the battery to fix something works against you. Unpluging the battery causes EEC to memorize all the sensor data as baseline and normal. If it memorizes a bad sensor it will take it longer to call it a liar. Fr did however give EEC a very broad idea of what the sensor should be reading in its permanent ROM memory, so it will catch on to failed equipment sooner."

marshall_mosty
02-12-2009, 10:53 PM
Okay,
Went to the dyno today... had really good luck. It was either the coil or the ECT sensor. Also, engine must have loosened up since I honed it last.

I'm going to need some ballast. 2951 is the new minimum weight.

310.71 HP / 311.44 TQ

I should be somewhere around 2825 with the new splitter and add 125lbs of lead should do the trick.

AI#97
02-13-2009, 09:54 AM
glad you got it figured out! Gonna be nice putting that ballast where you can use it too!