Misfire question, please help if you can.

FIMotorMX-3 · Post by **FIMotorMX-3** » November 25th, 2005, 6:41 pm

Well, the little annoying problems continue.. My car has been misfiring for about a month or so, maybe more. I've always noticed some popping and hesitation but wasn't sure what it was, now that I have my exhaust done, it's definately a misfire. I can hear it and it's been getting noticably worse. When I did my ze swap, I changed the disty and plugs. That was in May. Just withing the past couple weeks, I've turned in the disty and replaced it under warranty. Thought that might fix the problem. Still missing. Next was the plugs, another set of ngk copper plugs set at .44 gap. still missing. Then I went to the plug wires. got accel thundersport 8mm, still missing. All this time, I've put some fuel system cleaner in the car and it's helped for a day or two, then the missing comes back. So I thought I narrowed it down to the fuel system... I thought. Changed out the fuel filter. Still missing. The car isn't running as bad and the missing is definately not as noticable but it's still there. I'm affraid it could be the injectors but i'm not ready to shell out that kind of money, and I'd like to do the turbo set up so I don't wanna replace injectors until I'm possitive whether I'm replacing with stock or larger injectors. Is there any other possibilities I could be overlooking that might be cheaper solutions to this problem or am I completely screwed and best bet is to drive her off a bridge? Thought maybe it could be vris, because it would miss at the vris points but that was just my imagination i think cause it's more frequent then when vris engages. I haven't checked compression on the car and not sure how hard of a job that is, or what the readings should be at. The missing occurs during regular or hard acceleration and sometimes at cruising. I think I've noticed it at idle before but not recently. Please someone have some good news and tell me this doesn't sound like it's going to be something major or expensive..

P.S. The car seems to be running a little leaner at times than it used to. my air/fuel gauge would always run where the led's would bounce between the lean mark and 3/4 rich. the 1/2 mark being perfect mixture. Now the gauge only reads from the lean mark to about a 1/3 to almost half way. Unless I get on the gas, then I'm blowing black smoke and the gauge runs back up to 3/4 so I'm definately running rich at full throttle. I don't know if that description helps with anything or if it even makes any sense.

hgallegos915 · Post by **hgallegos915** » November 25th, 2005, 6:46 pm

I hae the same problem, not the fuel pump, not the ignition..my next step is injectors. Last is timing belt. After that.. ??? im lost

FIMotorMX-3 · Post by **FIMotorMX-3** » November 25th, 2005, 6:56 pm

I have been told by another guy I only met that night, so I'm not sure how true it is but, I got on the car one night when a turboed crx pulled up to me and when I pulled away from him and shifted, I supposedly shot a flame out of my exhaust between shifts??? I didn't think I would be able to do that unless I was spraying or boosting. Don't know if that helps explain where the misfiring could be from. He thought I sprayed him and flashed his highbeams to pull over and compare our engines.

markmclean · Post by **markmclean** » November 25th, 2005, 7:16 pm

well first things first...one night after dark start the engine and with a spray bottle mist some water over the plugs, if you see a spark, youll know its a plugwire shorting out...also look at your coil for bulging or cracks....next check for vacuum leaks or a leaking TB gasket or intake gasket. running the motor and spraying a little injector cleaner around the intake surfaces, if the engine revs up, it indicates a leak. after that, try running codes through the dignostic mode..if none of these help, get off the wallet and pay for some diagnostic time..at any rate, good luck

93_mx3_gs · Post by **93_mx3_gs** » November 25th, 2005, 11:57 pm

FIMotorMX-3 wrote:I have been told by another guy I only met that night, so I'm not sure how true it is but, I got on the car one night when a turboed crx pulled up to me and when I pulled away from him and shifted, I supposedly shot a flame out of my exhaust between shifts??? I didn't think I would be able to do that unless I was spraying or boosting. Don't know if that helps explain where the misfiring could be from. He thought I sprayed him and flashed his highbeams to pull over and compare our engines.

I used to do that all the time in my 4.3 S-10 =)
Send a nice 4 foot flame out the tail pipe. Sounds like you aren't burning all your fuel in the combustion chamber.

PATDIESEL · Post by **PATDIESEL** » November 26th, 2005, 1:25 am

There are only a few sensors that deal with air/fuel so lets start there. First are the O2s. How old are yours?
Second is MAF. Are you still using the K8 MAF, and I'm assuming a curved neck Millinea intake??
Timing could be off. Did you change the belt when you did the swap?
Did you time the engine if you replaced the belt? If so check the timing with a timing light and make sure it is still timed correctly.
Could be a fuel pump on its way out. Check the online shop manual for how to test it. It tests off of resisitance if memory serves me.
Injectors could be crapping out. They work off of resistance too (ohms) so test them per shop manual. This will tell you if they need to be replaced.

One of those should be the problem. I really don't think that a vaccum leak will cause a lean condition or a backfire. Since you just replaced the wires I'd pass them up for now. You cannot run a ZE in diagnositc mode and I don't know anyone wh ocan scan a ZE b/c they don't have the correct programs to tell what the ECU is saying. (that is if you have a ZE ECU) If you have a remapped K8 you should be able to check the codes yourself.

Answer my questions and we'll go from there. Shouldn't be expensive to fix (unless you need O2s, they cost about 150.00 each and we have two), but may take some time to find.

hgallegos915 · Post by **hgallegos915** » November 26th, 2005, 2:06 pm

hmm o2 sensors... i havent tought od that before! so what will our crs do if we discoinnect o2 sensors? i know they dont give codes because i tried driving without it to see if i can see any difference and ecu didnt give a crap,, sicne the codes are for inversion.. hmm nice idea imma try that also.

FIMotorMX-3 · Post by **FIMotorMX-3** » November 26th, 2005, 5:21 pm

Well, Pat, since we've gone over what I have as far as swap, I'm assuming that's just a generalization for both me and hgallegos' questions. My car is curveneck ze millenia manifold, with the kl36 ecu. I did't do the timing belt when I got the car because of the low mileage and my rushing to get the engine in the car so I could get down here to school. The wires, plugs, disty, cap, rotor, and fuel filter are literally brand new with less than 200 miles on all of them. filter has less than 50 miles on it. I am going to hit the car with a timing light tomorrow as well as a compression test as long as the weather holds out. The car has to make it back up to jersey (900 mile trip) by wed morning. My girlfriend also recommended a fuel injector cleaner that is basically a can with hose that you hook up to the intake plenum and it sprays directly into the injectors to clean them while the car is idling. The car will blow white smoke out of the exhaust until all the can has burned off and cleaning is finished. Jiffylube supposedly has this same treatment. Has anyone else either heard of this or used this method? Is it effective or a waste of time and money? If it's possibly clogged injectors, hopefully that will help. Hopefully timing light and compression test will help narrow down the problems a little.

hgallegos915 · Post by **hgallegos915** » November 26th, 2005, 10:30 pm

in my case I did the timing light and compression and it all came back ok. Im replacing the injectors next week

PATDIESEL · Post by **PATDIESEL** » November 26th, 2005, 11:57 pm

I've known many shops that use that type of fuel system cleaner. Just make sure to do it in a VERY open area. I took Justin to the hospital one night after he did that to two cars while at work (Kaufmann Tire). The hospital said his blood was full of something that was blocking the oxygen and he was basically suffocating from the inside. Scary, but he was fine.

FIMotorMX-3 · Post by **FIMotorMX-3** » November 27th, 2005, 4:32 pm

Damn, guess that is some good stuff to huff... Well I don't know if I have to go the route of the injector cleaner. I didn't do the timing light but I did do the compression test. 180 cyl 1, 200 for the other five. Then we started to play with the throttlebody. The thing was sticking and caked with carbon, and holding it at about 2000 rpm, the idle fluctuated giving us the assumption that the tps is shot or on it's way out and that may very well be what's causing the misfire. When the tps is malfunctioning it causes sporatic bursts of fuel from the injectors which could very well be what's causing the bogging and misfiring. The car does run rich for the most part. It's noticable by the black soot in my muffler tip and rear bumper. We turned the tps about 40 degrees and the trottle response is a little smoother and the idle smoothed out drastically but we didn't have a voltage meter to test the tps. I am going to try to locate a volt meter tonight, possibly buy a cheap one so that we can do the test and possible eliminate one more culprit and hopefully find the problem. it's starting to get annoying and a little discouraging.

Who has the best price on TPS? I think my girl priced it out for me at either autozone or advance not too long ago and she said it was like 149? Anyone hear of it being cheaper elsewhere?

PATDIESEL · Post by **PATDIESEL** » November 29th, 2005, 2:11 am

Check the online shop manual for the ohm resistance test ot know if hte TPS is bad. I've not seen many go bad before, but that could be the problem. Also try cleaning the TB out and then adjust the TB by ear. loosen the TPS screws just a tad (where you can turn it but it is stiff to turn) then jump ten and ground with car off and then crank the car, turn the TPS clockwise untill the radiator fan turns off, then rotate it counter clockwise untill the fan turns back on. You want the TPS just before the fan turns on. Retighten the TPS screws, turn the car off, pull the jumper, crank car. The idle should be better and when you pop the throttle it should go up, not down then up. If this seems ok, then your problem is fixed. I tune all my TPSs the manual way. I've tried using a meter and just haven't had good luck with it. (I was an electrician for 4 years so using a meter is easy for me and usually I'd say do it the proper way, but not in this case)

As for where to get the TPS if it is bad, check Rockauto.com or any of the other major chains. Usually Rockauto has the best prices, but after shipping sometimes it is easier to get it from a local place.

FIMotorMX-3 · Post by **FIMotorMX-3** » November 30th, 2005, 9:38 am

Would there be any reason why when I jump ten and ground, my car won't start? I've never been able to get the car in diagnostic mode with the pins jumped. just cranks and stalls right out.

PATDIESEL · Post by **PATDIESEL** » November 30th, 2005, 10:43 am

OMG, your car is wierd. How can you time the motor witout being in diag mode?
I would imagine it has something to do with your timing being off that it won't run on that rich of a fuel mixture (diag mode is super rich to combat knocking if the knock sensor goes off. Diag mode is also what the ECU defaults to if it finds other fuel/timing related problems)
To be honest I'm getting tired of answering these posts. You need to check the timing belt yourself and then tell me what you find. Otherwise I'm just wasting my time answering questions. I'm not trying ot be mean, but from the beginningthat is what I've told you to do. I know that you are notthe most technically savvy, but checking the timing marks is not hard. Taking all the stuff off of that side of the motor is the most difficult part of the whole thing.

FIMotorMX-3 · Post by **FIMotorMX-3** » November 30th, 2005, 8:35 pm

I have no problem checking the timing..... When I have a gun... No timing gun, it's kinda hard. I'm leaving for Jersey in two days and didn't have the time (or money until I go back to work next week) to rip the engine apart to just go ahead and do a timing belt and waterpump. If and when I get a timing gun (I have one in Jersey, that I checked my timing with when I swapped my engine), I'll let you know what I find. I was hoping that maybe the symptoms would suggest something quicker and less labor intensive with my schedule, trying to move out of my apartment making it hard to tear at my car.