SRT-4 Misfire, No codes

[contraption22]

Hello all.

Just as I was about to leave for SDAC, my SRT-4 developed a severe missfire condition. This was not load or boost related, although it was more perceptible under load. No codes were displayed.

I parked the car for a week while I was away at the convention, and since I have returned, I have driven it a few times in an attempt to get the issue to reoccur, but it has not as of yet.

Here is how it started.
A few days earlier, I had cleaned the engine compartment with some Simple Green and water, like I've done many times before.
I replaced the battery which had been showing signs of weekness for months.
It was hot out. Over 95 degrees.
I had just filled the car up with fuel.
Drove it about 20 miles and stopped for a quick bite to eat. Maybe 20 minutes.
Parked it facing up an incline.
When I returned and started the car, it started misfiring immediately.
Drove it about another 5 miles to a friend's house. Did a quick check of the plugs and wires. All seemed fine.
Unplugged the cam sensor. Car wouldn't start.
Plugged the cam sensor back in. Misfire was gone.
Went on a short test drive. No issues.
Disembarked for SDAC, and within 5 minutes, it started to act up again.
Decided not to trust it.
Drove it about a 1/2 hour back to my house. Misfire issue came and went along the way. No real pattern to it that I could tell.
Still no CEL, no codes.
Disconnected the battery in fear of some electrical issue, and left for Detroit in Gary's car.
Again, since I have returned, I have driven the car several times with no issues.

I have borrowed a Snap-On brick scanner, but no instructions. If anybody has any tips, for that, I would appreciate it. I'm told there is a way to read crank and cam position sensor pulses, but I do not know how.

Any help/suggestions would be appreciated.

Thanks,

Mike

[BadAssPerformance]

Sounds like its time to sell it an get an Evolubaru yo!

LOL!

Random thoughts...

Did it make it more under boost or while driving gently? SRT-4 notorious for ignition wire issues, especially if strut tower brace added and close to wires.

Did you check the plugs?

Any oil coming out of cam sensor connector? They like to crack and get oil inside them.

[contraption22]

Sounds like its time to sell it an get an Evolubaru yo!

LOL!

Random thoughts...

Did it make it more under boost or while driving gently? SRT-4 notorious for ignition wire issues, especially if strut tower brace added and close to wires.

Did you check the plugs?

Any oil coming out of cam sensor connector? They like to crack and get oil inside them.

Thanks, JT. Considering trading it on a BRZ STi Spec C. lol

I don't know if it misfires more under boost, but it is certainly more noticeable. I chalked that to having higher cylinder pressure.

I will recheck the wires and Ohm them out. They are Magnecores and look to be in good shape, but are 8 years/50,000 miles old.

Plugs are fresh and look fine.

I will check the cam sensor as well. No signs of oil or cracking externally tho.

[1qk4dr]

Ohm the wires and check out the magnet behind the cam sensor. Magnets will loose their strength in higher heat conditions and could begin to fail.

[contraption22]

Ohm the wires and check out the magnet behind the cam sensor. Magnets will loose their strength in higher heat conditions and could begin to fail.

Thanks.

Do you mean just pulling out the magnet and seeing how powerfully it draws itself to steel? It should be fairly powerful?

[BadAssPerformance]

Thanks, JT. Considering trading it on a BRZ STi Spec C. lol

Aw3s0m3!!!111!!!


I don't know if it misfires more under boost, but it is certainly more noticeable. I chalked that to having higher cylinder pressure.

I will recheck the wires and Ohm them out. They are Magnecores and look to be in good shape, but are 8 years/50,000 miles old.

Plugs are fresh and look fine.

I will check the cam sensor as well. No signs of oil or cracking externally tho.

I've heard mixed results with Magnecor wires on SRT-4's. Chrysler says only use Mopar (obviously) and many have had no issue. Weren't we talking years ago about them being able to reach the plug or not?

The 2.0L/NA 2.4L DOHC sensor I'm more familiar with like to crack on the inside part where teh cam is and fill up with oil.

[turbovanman²]

I would replace the wires and go from there.

[Mopar318]

Check to make sure the TIP has a line going to it, and the fitting on the cold side pipe that runs to the solenoid.

[Shadowv4l]

I know this might sound funny but.... serp belt old? I had a 4.0L at the dealer giving me strange misfire issues that I couldnt pin point. I replaced the cylinder head, piston rings and all kinds of random crap under the direction of the service manager and other techs. The last thing I replaced was the serp belt on a hunch I had, turns out that was the issue causing a misfire. I will never forget that, I wish I could've taken a picture of my manager's face when I told him I replaced the serp belt and the misfire was gone. lol

also, coil packs do some strange sheit and the cam sensors on neons get a buildup of a metal paste from the cams which can cause some funky readings. I have already removed and cleaned cam sensors and re-installed them and had them work.

[Shadowv4l]

also, if you overfill the gas tank fuel can get into vapor lines and cause misfires and no-start conditions especially in 2000 - 2007 mini vans. Maybe it is possible by parking on an incline with a overfilled tank that the fuel got into vapor lines or canister causing a misfire condition upon start-up and while driving the fuel sloshes around also getting into lines and creating the same issue. This also may not show a code because the misfire is hit and miss and the evap system doesnt have a check for a overfill condition. The car wont show a misfire code unless it sees a constant pattern of misfires within a certain amount of time.

[RoadWarrior222]

Teh 2G neons I've "known" seem to like eating coil packs and are fussy with wires.... and have had cam sensor issues... also seem to need frequent injector cleaning.... but I've not been familiar with an SRT-4, but presume that if any of those things are due to heat baking stuff, then the turbo can only be worse for it.

---------- Post added at 06:47 AM ---------- Previous post was at 06:45 AM ----------

Oh I have been suspicious about spark flashing over to the hood on neons before.... that's sort of a bad wire thing but seems you have to keep 'em real flat in order not to encourage it.

[Keito]

also, if you overfill the gas tank fuel can get into vapor lines and cause misfires and no-start conditions especially in 2000 - 2007 mini vans. Maybe it is possible by parking on an incline with a overfilled tank that the fuel got into vapor lines or canister causing a misfire condition upon start-up and while driving the fuel sloshes around also getting into lines and creating the same issue. This also may not show a code because the misfire is hit and miss and the evap system doesnt have a check for a overfill condition. The car wont show a misfire code unless it sees a constant pattern of misfires within a certain amount of time.

Interesting. Mike, did you stuff it full of fuel before the trip?

[contraption22]

also, if you overfill the gas tank fuel can get into vapor lines and cause misfires and no-start conditions especially in 2000 - 2007 mini vans. Maybe it is possible by parking on an incline with a overfilled tank that the fuel got into vapor lines or canister causing a misfire condition upon start-up and while driving the fuel sloshes around also getting into lines and creating the same issue. This also may not show a code because the misfire is hit and miss and the evap system doesnt have a check for a overfill condition. The car wont show a misfire code unless it sees a constant pattern of misfires within a certain amount of time.


Interesting. Mike, did you stuff it full of fuel before the trip?

I was thinking that might be an issue. I definitely filled it. It's now down to below 3/4 tank and has had a week to settle out. I still cannot get it to misfire. Put another 40 miles on it last night.

Thank you all for your suggestions.

[RoadWarrior222]

Or, of course, you were just a little too overzealous or unlucky with the water while you were cleaning this time and the dodgy connection dried out.

[contraption22]

I've heard mixed results with Magnecor wires on SRT-4's. Chrysler says only use Mopar (obviously) and many have had no issue. Weren't we talking years ago about them being able to reach the plug or not?

Yes, I remember that. I had borrowed the plug wires off my DOHC 2.0 Neon and they did not seem to make good contact with the spark plugs. I cannot remember what the difference was. I know the spark plugs themselves are different between late and early dohc heads. Early ones have gasket seat. Later ones have tapered seat.

Oddly, MSD does not offer a part number for the early DOHC, but they do offer it for the later engines.

Magnecore lists the same part number for all DOHC engines. 1995-2010

[BadFastGTC]

Mike, you may also want to mist each wire individually with water to see if the insulation is breaking down. Hit the coil also.

[contraption22]

Mike, you may also want to mist each wire individually with water to see if the insulation is breaking down. Hit the coil also.

I will do that. I should have done that by now. When I worked in a shop, that was the first thing we would do to Chrysler 4cyls that came in with misfire codes on rainy days.

[DodgeZdad]

Couple of times I got a little misfire starting up cold after a previous day of running high speed in the rain.

I almost pressure washed my engine before going to SDAC 22 but ran out of time. Guess I'll tape all the sensors up if I wash it.

[1qk4dr]

Thanks.

Do you mean just pulling out the magnet and seeing how powerfully it draws itself to steel? It should be fairly powerful?

It will still be strong enough to draw itself to steel and there is no easy way to tell that it has failed. It should trip a code 344 but worth a look. The magnet is about a 20 dollar replacement.