constant misfiring...

[smg944]

searched through several threads. there are tons of different types of misfire. i found one that related to mine, but didnt work. ( cas sensor ). anyway i have a constant misfire its a 91 tsi with minor bolt ons. it studders at idle between 400-800rpms. when i drive it it misses all the time. part throttle is much less but still does it. i cant really build boost because it misfires so bad. seems like its only on 2 cyl. no cel comes up. its a very consistant miss, kind of sounds like i am driving a wrx if that helps explain it at all. any help appreciated.

 

[pitbull419]

You could have a faulty plug.
Happened to me about a week ago.
I pulled the plug out still looked new.I put it on the wire and turned it over,it fired.
Put it back it was still missing.
I bought a new plug and put it in missfire went completely away.
A faulty plug sometimes wont fire or fires weak under pressure.
Worth it to try it out.
Also i would do a compresion test on that cylinder.

 

[chetvram]

I had a simlilar problem with my car, after checking over my plug wires I found one wire had heated up and burned a hole through the casing and was arcing to the Intake manifold.

 

[IllusionX90]

I had the same problem with my Talon last week. I just picked up the car and not even two days later the car was puting and misfiring. I would get backfire from 2nd or 3rd gear, dropping rpms etc.

It turned out that my plugs were fine and the fuel injector on the 2nd cylinder was bad, as soon as the injector was swapped the car ran great again. So if you replace the plugs/wires and its still doing it try doing a test on the injectors. Good luck.

 

[laserspeeddemon]

Whoa, way too much causes for that.

Start with new wires and plugs (NGK BPR7ES)
If the problem persist try checking the fuel injectors by connecting a timing light to them.
Next you can check compression.

Check those and come back here, we'll go from there.

 

[xioca]

Pull the spark plug and look for corrosion, I had a very small amount of moisture in mine that caused it to miss, simple fix but took forever to diagnois. Also if you have dirty plug wires, look for cleans spots which indicates it may be arcing.

 

[smg944]

sorry on the delay. i changed out the plugs to bpr7's also changed out the wires to brand new ngk's. i noticed not all wires were the same so it was repaired poorly. so that fixed the missing. the old plugs were white which isnt to nice. i am getting some leaning out. i think its from the tps. also i can seem to hold any boost, it just fall off from 7psi to 2psi. i tried a boost controller and everything. no luck... did a boost test and i can only get it up to 12 psi. then it falls right to 0 within 2-3 seconds. i hear air leaking out from the injector o-rings and tb gasket. but would that really cause that bad of a boost issue? my other car you can drill a 1/4" hole in the intercooler piping and it will still get full boost.

 

[laserspeeddemon]

sorry on the delay. i changed out the plugs to bpr7's also changed out the wires to brand new ngk's. i noticed not all wires were the same so it was repaired poorly. so that fixed the missing. the old plugs were white which isnt to nice. i am getting some leaning out. i think its from the tps. also i can seem to hold any boost, it just fall off from 7psi to 2psi. i tried a boost controller and everything. no luck... did a boost test and i can only get it up to 12 psi. then it falls right to 0 within 2-3 seconds. i hear air leaking out from the injector o-rings and tb gasket. but would that really cause that bad of a boost issue? my other car you can drill a 1/4" hole in the intercooler piping and it will still get full boost.

Yes, it can. You can't compare the 1.3L rotary motor to a 2.0L 4-stroke motor.

Also you might want check the O-ring on the BISS (Idle) screw on the TB, if the TB gaskets are leaking, chances are that is too. If you are not pressed for time, you can send me your TB and new o-rings with a little cash (like $25 to cover shop usage fees) and I can rebuild your TB as well. That should elminate the major boost leak area with the expection of the valve seals and EGR. To test that set the timing mark on the crank shaft to approx. 12 'o' clock, pressurize the tract and open the oil cap, it will be noticable loud, a small hiss is not a big deal. But if its screaming, then they need to be replaced. To check the EGR just listen into the tailpipe. There should be no audible hissing coming out of the muffler.

 

[smg944]

really i didnt know boost leaks did that much. im so used to the rotary. anyway what do i need to get my tb rebuilt? because i heard some hissing where the spring is. also it is leaking from the idle screw (biss). i got some pics of the valves i would like you to see. they dont look so nice. any type of internal cleaning that can be done on these? on the rx i can run water through the vacuum hose to clean the internals, i am figuring its not the same for the dsm.

 

[smg944]

here is a pic of another cyl.

 

[laserspeeddemon]

Yuck! That engine has not been maintained very well.

You need two Oil seals from Chicago Rawhide, part #3930 (Assuming you indeed have a 1991) . These seals are ONLY sold at Motion Industries, so find the local supplier in your area.

and you need two machine screws. Once you get your TB off, take it to Home Depot and compare and match them. You don't need to get the screws out. Just match the shape and size and send them to me. If you can't get screws I can pick them up for you, I know which ones to get.

But the Oil seals, you have to get. It took me 4 months for the local Motion Industries to get mine in. They kept f*cking it up.

 

[smg944]

dam that long for seals. i am going to go to home depot and check on those.

any ideas to clean up the internals...

 

[xioca]

dam that long for seals

Run to a hardware store and pick up a couple of rubber O-rings the size of the retainer you pull out. Coat in silicone grease and press into the metal retainer and insert it back onto the tb shaft. This may not be the correct method to do it, but mine has lasted for over 6 months, and for less than a dollar I could always do it again.

 

[ndsti]

You could try seafoam. Just search for seafoam and you should come up with alot of read material.

 

[laserspeeddemon]

Run to a hardware store and pick up a couple of rubber O-rings the size of the retainer you pull out. Coat in silicone grease and press into the metal retainer and insert it back onto the tb shaft. This may not be the correct method to do it, but mine has lasted for over 6 months, and for less than a dollar I could always do it again.

My moto is do it right, do it once. Not only do you save time, you don't have to worry about the risk of anything going wrong in the future.

You could try seafoam. Just search for seafoam and you should come up with alot of read material.

I am honestly not a fan of seafoam. It basically just breaks up composite build-up and let it run through the motor. Who wants hundreds of debris particles bouncing around in the cyclinders? The best way is to do a rebuild. On a side note, the valves you pictured is probably the exhaust side, which is bound to have carbon build up on it. Yours is just a little excessive.

 

[92awddsm]

I am honestly not a fan of seafoam. It basically just breaks up composite build-up and let it run through the motor. Who wants hundreds of debris particles bouncing around in the cyclinders? The best way is to do a rebuild. On a side note, the valves you pictured is probably the exhaust side, which is bound to have carbon build up on it. Yours is just a little excessive.

Actually, that is the intake side. By the looks of the clean ports and the buildup on the backside of the valves, I would be willing to bet that you have some leaking valve seals.

 

[smg944]

what symptoms do you get when the valve seals are leaking? if they are leaking i am ready to pull this head off and completely clean it up. i cant imagine what the pistons look like.