Random misfire at cruising speed

[DeathtoHonda]

Ok, this is my first Thread. I have a stock 1990 Talon TSI. I wired in a 2g MAF i did a complete engine rebuild and brand new 16g turbo. It runs Awesome under load and under boost. While im driving to work i drive 30 miles one way and im cruising at 50 mph or 40mph or any time i stay at one speed the car runs perfect then it starts to misfire and slow down if i press on the throttle it stops and i go back to cruising speed it starts again. I still have to EGR valve on but vacume lines cut off. I been a tech for 8 years now i know at cruising speed the ECU will lean out the fuel mixture and open EGR valve. Could that be my problem? Can i wire in a black top CAS on my photo light sensor?

 

[livetoriderm7]

Have you looked into your plugs being fault or your coil pack? I know I run copper tipped plugs in my GST since the spark is colder it helps keep the engine healthier.

 

[donniekak]

How are you tuning to compensate for the 2g maf?

 

[latkins09]

Maybe ## plugs are gapped to big are you using copper plugs

 

[95blackGsTurbo]

You sound like you are on the right track with the EGR valve. If all of the lines are capped off then it should essentially not be functioning. If however it is weak or the diaphragm is bad it could be opening up at cruising and the ECU is not compensating for it. I would block off the EGR valve and see if that helps your problem. If is always a good idea to check to make sure it has the correct plugs but that would cause more problems under heavy load than cruising. Also definitely make sure you have at least a SAFC to tune in for that 2g MAF.

 

[DeathtoHonda]

Well i thought about having my 2g maf. I bought a N/T fuel regulator which the turbo reg is 38 lbs and N/T reg is 48 psi. That helped richen my mixture to compensate for the extra air and i found a bad injector, so far since last weekend it running very well. I found my bad injector cause one day it was really hot and i went into the store came out and car running on 3 cly. so i took all injectors out took a 9v battery and used old wire lead and open and closed all injectors but one got really hot real fast then quit working so i bought a reman injector and so far its running with out a miss. I also replaced all plugs with bpr7es i think thats the number i cant remeber. anyway its the hotter plug NGK makes and gaped at .028 . And i also filled the EGR valve with high temp silicon on exhust side. I read the threads and i apreciate your guys help.

Oh and i reset my timing it was like 15 deg advanced to far. i grounded the timing plug and took timing light both cams lined up and crank at 5 deg. that helped ALOT...

 

[2g awd dsm]

I am having this same issue, cruising it misfires but as long as I'm accelerating and decelerating it doesn't misfire, only when cruising. So should I start with checking my plugs gap?

 

[VRP]

90 CAS has the pigtail wiring to run over to wirewall....I had one that the insulation on the wires for the pigtail were cracked right where they go into housing of CAS...Caused a similar problem.
Also Injector wires cracked from heat can cause similar problems..

Hope this helps.

 

[Bmxr152]

Did you ever figure the misfire out? Im having the same issue. Only at cruise and between shifts, under any load or doing a pull it runs fine. I checked plugs and all looks good. I also did a blt with only slight leak on throttle seals, but with sd I don't think that's really a issue. Any suggestions,