Overboosting and random misfire!

[DsmPimp20]

Hey all, I love my DSM but, lately I just wanna strap some C-4 to it and blow it into a thousand pieces of metal. Anyways I had a 1st gen head swap done a while back and recently my car started random misfiring. I never had the barometric pressure switch thing done and I was wondering if anyone can tell me if the Barometric switch will fix my problem. My car will drive fine on city streets but, between 3000-4000 rpm at cruise my car goes from smooth sounding to a machine gun type sound out the exhaust, as soon as I let off the gas it will go away but, it comes back once I get back up to that rpm range at cruise. My mechanic has checked everything on my car I had new plugs, wires, a new coil pack, and basically anything that involves spark has been checked out or replaced. Problem still persist we are going to try the barometric switch mod tonight or tomorrow. Now as for problem number 2: I had an AFC on my car and my mechanic sold me a MAF-T which he said was better than the AFC so we took the afc off and we are now running the maf-t which is placed right before my throttle body so it gets the last reading possible of air intake. Well, ever since he did that I took my car out right after install and I WOT'ed it out and I hit fuel cut because my car was boosting up to 30psi, My boost was set at 18 psi before the MAF-T install. We went over all my vaccum lines and discoved that my vacum hose off my actuator had a hole burned into it because it was resting on my hot intake. we fixed it and we fixed all the boost leaks. Now my car boost up to about 20 psi and I just let off because I am afraid it will keep climbing. We can't get my boost to go below 20 psi and I don't have a BCS on my car because I guess 1st gen heads don't have them. My mechanic said that he thinks my ACTUATOR IS stuck either opened or closed I forgot which he said. I was wondering if anyone has had the same problems>? I know it isn't a boost problem or an MBC problem because we put on another MBC and it did the same thing. All my line are hooked up too. HELP a brother OUT!

 

[TRBOBLU]

Yes the baro. mod will fix the car but I advise strongly against it. It's a band-aid fix, don't ever do band-aid fixes unless you are just trying to get home to avoid a tow. I've read and talked to many people who have done it and have had engine failure shortly down the road. My advice is to get DSMLink, it will fix the problem and is the single best tuning tool next to a standalone setup.

 

[TRBOBLU]

One more thing. Just curious, do you have a logger? If so when the car starts sounding weird, let off the gas and delete the CEL's via the logger. I had about the exact same problem with my setup. I would get the random missfire code and the ECU would shut down the number 1 cylinder, sounded just like a Subaru but when I let off it would run fine. I found be deleting the codes the car would run fine for about 300 miles than throw the code again. I drove my car like that for 3k miles before finally getting DSMLink to solve the issue.

 

[talonguy91]

Was the misfire occurring before or after you installed the the MAF-T?

 

[Ultimatedsm]

Time for a DSMLINK and I have a brand new 2g link laying around. Let me know if you are interested.

 

[DsmPimp20]

Was the misfire occurring before or after you installed the the MAF-T?

It was happening before the MAF-T was installed. No I don't have a logger anymore I sold it. I don't wanna have to buy DSM LINK if I don't have to, I have enough money dumped into this damned car. You think my motor will give if I do the Baro fix? DAMN this car to hell! Why does DSM LINK fix the problem? is it because it can erase the codes indefinately or something? Do you have an answer to my overboost problem?

 

[Ultimatedsm]

DSMLINK has a feature where you can disable mis-fire detection. That means the ECU will not try to detect misfires at all and your car will fine.

 

[talonguy91]

Correct me if I'm wrong, but I thought when you install a MAF-T you could possibly see a very slight increase in boost because of the more free flowing air. You said that after you fixed the burned hose on the wastgate actuator that the boost went to 20 psi but that u let off, did you try and stay on it a little more to see if it boosted past 20 psi.Because if it was 18 psi before and it only goes to 20psi then wouldn't that be ok and all you would have to do is correct what you need to on the MAF-T for the increased flow?

 

[DsmPimp20]

Correct me if I'm wrong, but I thought when you install a MAF-T you could possibly see a very slight increase in boost because of the more free flowing air. You said that after you fixed the burned hose on the wastgate actuator that the boost went to 20 psi but that u let off, did you try and stay on it a little more to see if it boosted past 20 psi.Because if it was 18 psi before and it only goes to 20psi then wouldn't that be ok and all you would have to do is correct what you need to on the MAF-T for the increased flow?

I turned my boost controller all the way down and it was still hitting 20 psi! I did let off because I was afraid off hitting fuel cut for the 8th time. I neglected to say that my intercooler pipe blew off and we fixed that at the same time that we fixed the vacum line that was connected to the wastegate actuator! I hauled ass in my car about 8 times overboosting and I adjusted my boost controller after every run and it never went down 1 psi! Ugh does the wastegate actuator

 

[talonguy91]

Maybe your wastegate actuator arm is bent for some reason and is causing it to stay closed causing the overboosting.Can you adjust the actuator arm? If so maybe you can adjust it from there to possibly open sooner that way it doesn't boost so high.

 

[DsmPimp20]

Maybe your wastegate actuator arm is bent for some reason and is causing it to stay closed causing the overboosting.Can you adjust the actuator arm? If so maybe you can adjust it from there to possibly open sooner that way it doesn't boost so high.

I am going to slap on a new wastegate today I will keep you posted and I am getting ready to do the barometric fix so, I will let you know if the problems go away.

 

[DsmPimp20]

misfire was fixed with barometric switch

 

[talonguy91]

Good stuff, now its time to fix that boost problem keep updating I'd like to know how things work out for you.

 

[anmsk8r]

I was having a problem with overboosting as well(up to 20+ psi). I thought it was the MBC at first so i connected a hose from the wastegate directly to the turbo outlet nipple and it still overboosted. That led me to believe that the wastegate was stuck shut, but when i hooked the BCS up it didnt overboost.... so I checked the tube going from the MBC to the wastegate and noticed it was bent by my big custom intake pipe and boost pressure wasn't getting to the wastegate. I messed with the intake pipe and the hose and got it to where the hose wasn't bent anymore. ow it goes up to the correct pressure setting and stays. Maybe you have the same problem.

 

[DsmPimp20]

I was having a problem with overboosting as well(up to 20+ psi). I thought it was the MBC at first so i connected a hose from the wastegate directly to the turbo outlet nipple and it still overboosted. That led me to believe that the wastegate was stuck shut, but when i hooked the BCS up it didnt overboost.... so I checked the tube going from the MBC to the wastegate and noticed it was bent by my big custom intake pipe and boost pressure wasn't getting to the wastegate. I messed with the intake pipe and the hose and got it to where the hose wasn't bent anymore. ow it goes up to the correct pressure setting and stays. Maybe you have the same problem.

I gotta by some new clamps today so that my couplers will stop blowing off my maf-t, then I should be able to hit full boost without blowing off my couplers. I will let you know if it fixes the boost problem. DSMer's are awsome!

 

[DsmPimp20]

problem was solved. Oh I got a new wastegate too although I am not sure as to which fixed the problem. Peace!

 

[95gstsilver]

what kind of barometric switch did you get. Size? ohm? and what ever else i would need to know.