13173

Alright, had my car tuned up this past saturday. Once we got past all the weird problems we had at first we got the car tuned up.

I bring the car home and unload it off the trailer the next day. Take it up the road and once I hit 3rd gear (full boost in that gear) it wants to break up / misfire. Well, immediately I think plugs. I re-gap my NGK Iridium, 8 heat range plugs down to .018". That did not take care of the problem. I have also swapped on another used cap and wires and swapped in some brand new plugs. The problem stays the same.

Now let my go further in depth on the problem. Currently my car is tuned for 14psi in 1st gear, 16psi in 2nd gear, and 18psi from 3rd gear on. 1st-2nd gear did run fine, now yesterday afternoon it wanted to break up a little in the top of 2nd gear. 3rd gear is a different story, it wants to break up then run fine for a second then break up for a second then run fine again, and this occurs alway to rev limit. Its almost like a pulse, and the same for 4th gear.

The car is tuned on Neptune and I am using a Mac valve for boost control, so I obviously have the PWM mod in my ECU. I did have the older style RTP board, but it went bad with in the first 10 minutes of tuning, so I can give any details of the tune right now. It has been sent off to moates.net to access the situation. The distributor has a brand new coil and igniter in it that was installed Saturday during tuning.

Does this problem sound like a bad mac valve, the PWM circuit acting up, or does it sound like my ECU is going bad? I have checked over the wiring on the igniter and its all good and making good connection. I have heard a car or two that had nitrous and when they get down the track it almost sounds like their solenoids are pulsing and varying the amount of nitrous thus making the engine sound like its pulsing, but would the same happen to a turbo car? I tried to watch my boost gauge during this weird misfire, but I do not really see it fluctuating.

I wished this problem would have occurred while it was on the dyno, but of course my luck would not allow for that. It just so happens that when I have other knowledgeable people near me it doesnt misfire.

96 GSR-T

Breaking up is not going to be caused by a boost solenoid, you need to log your boost to see what that is doing....... have you checked your coil?

093turbo16

iTrader: (2)

What is the boost cut set at and do you have a boost gauge to monitor the boost?

The pressure will definitely change with IAT and especially going from the dyno to the street. It will usually need some tweaking over time to the IAT to duty cycle tables.

sleepencivic

try doing a run in 3rd partial throttle not full throttle see what it does might be boost cut like said above.

13173

Are you completely sure its not going to cause the engine to break up? I have seen some weird things in my day on a Honda. Some of which happened this past Saturday.

I am not sure what boost cut is set at, but maximum overall boost is 18psi so I cant imagine it would be to much higher than that.

Might I also add, I have never had a problem with this car ever breaking up over the past 3-4 years of it being turbo'd. Also, the same guy has tuned it since it has been turbo'd.

sleepencivic

who tuned it?

13173

A reputable shop over here in the south......

13173

Alright just went back out and did some more testing. I noticed that when the car breaks up the boost gauge is around 1.5 bar. My car was tuned to 18psi.....

Im not sure what the boost cut is set at just yet, but Im in the process of trying to find out.

If it is hitting boost cut, Im thinking that it could be busting up till it drops enough pressure until the MAP or ECU recognizes its safe to run the engine normal again and then it repeats. I did a part throttle pull and it busted up on that. I also hit it in 2nd gear which is supposed to run out at 16psi and it hit around 1.5 bar on my boost guage.

I think it may be hitting boost cut. Why wouldnt it do that on the dyno? Could my mac valve be bad and not working properly, or could it be something in that PWM circuit?

13173

I did a partial throttle pull all way up to about rev limit, and it did break up a time or two.

I think it may be boost cut, but I am not sure how accurate/inaccurate my boost gauge is. I also can not log anything because I do not have my RTP board in the ECU. Plus I have not heard back yet from the guy that tuned it where my boost cut was set. Im trying to get my tune emailed to me.

96 GSR-T

unhook your boost controller and just run off the wastegate spring, if it still does it the boost cut is probably not the issue.

TehGhett0P1mp

Whats are the a/f like when it is breaking up? My car kinda had the same issue and I found I was hitting a very lean spot on my map...then again the first tuner I took it to was an idiot so that would explain that..

13173

On the dyno a/f was looking good all across the board.....

Joseph Davis

Log VTS, VTP Request, and VTP. I've been through some problem cars, usually but not always with high mileage heads, that would intermittantly drop the VTP signal (due to borderline oil pressure). The ECU doesn't always kick a CEL 22 when this happens, if it's in and out quick enough. Also, just because the oil pressure is baaaaaarely enough to satisfy the VTP switch doesn't mean there's enough oil pressure for VTEC to engage. Low cam + a huge mass of fuel like high cam wants = bogging and misfires and unhappiness.

Last two cars that did it, only did it when the car had traction. You could roll into boost in second and barely haze the tires while accelerating very well, but as soon as third + traction came around they fell on their face.

Anyway, that's just one thing it could be. Good luck.

B18EG6

I don't have much to contribute, but I notice something very similar happen on my motor with Hondata. Even with the boost solenoid removed I still experience the same thing. In for some advice.

Joseph Davis

Provide datalogs or GTFO.

Same goes for the OP.

13173

On the street my car hooks exceptionally well with my M&H bias plys, even with the power my car makes now. There is some spinning involved but not as bad as one would think.

I have tried to roll into the throttle in 3rd gear and it does it. At first it didnt do it in 2nd gear but now at the top of second it will do it. Like I said, I am not sure how much my boost gauge is off, but it appears to me that I may have a little bit of a spike. I have not heard anything from Moates.net about my RTP, assuming they either have not received it yet or because of the holiday, but if I were able to log max boost pressure through that it would make things easier.

Also, directed towards J. Davis, when I hit 3rd it doesnt necessarily fall on its face, it still pulls, but while pulling it is busting up. The missing seems to be happening in a timed sequence.

I wished had people closer to me that I could troubleshoot in real time with. It makes random problems that you encounter much more manageable.

Joseph Davis

Timed sequence, meaning rythmic or single cylinder breakup?

If you have new/quality tune up components I would suspect a headgasket. Pull your plugs, check for coolant on the pistons from a ruptured headgasket. Do a compression test, a leakdown test, and pressurize the cooling system while the plugs are out.

13173

Seems to be its a rythmic sequence, and does not seem to be any certain cylinder.

I am running straight water in this engine and I do not seem to have lost any water.

I have not done a leakdown test on this engine, but I have done a compression test awhile back before the tune. Compression was fine at that point. I do have a leakdown tester though.

I have blown one headgasket and the only symptoms I would get then would be a random attempt at overheating. Replaced the hg and threw in my ARP's from my other engine and never had another problem with that. Thats not to say that I do not have an issue with the hg currently......

Joseph Davis

The last car I had this problem with didn't consume any coolant, or smoke, or overheat. headgaskets blow in a large number of different ways. Headgaskets seal coolant, oil, combustion chamber. They can blow in such a fashion that you have transfer - sometimes in only one direction, flip a coin to determine which - from chamber to chamber, chamber to oil, chamber to coolant, coolant to oil, etc.

That being said it could be something else completely different, but when making power your first order of business should always be making sure you haven't hurt the engine. From there you branch out to the fuel/ignition support systems.

13173

So just to make sure I understand correctly, you had a car with a similar problem as what I am currently dealing with, have a blown headgasket?

That is something that I have not really put forth much thought towards, but it could be a culprit, not going to rule that out at this point.

Personally, I do not think it is the headgasket, but stranger things have happened and I have definitely been wrong on occasion . Maybe tomorrow I will take it down the road and run it up on just wastegate spring, just to see what happens. If it the misfire does not occur I will know that I have a problem with either the mac valve, the PWM circuit, or the ECU as a whole. I have an extra solenoid that I can swap in, and it has a different part #.

13173

It cleared up a bit here and the roads dried off today. I just drove it up the road with the boost solenoid out of the loop. The engine was only running on wastegate spring which is 6-7psi. Registered just over 6psi on the dyno.

The car performed great. No rythmic misfires and pulled all way to redline 1-3 gear. Albeit, the car was a turd on just wastegate spring, but this lets me know that something is going on in the PWM circuit or that mac valve. I have another mac valve that I can try, and I am not sure that its the valve itself that is going bad. Reason I believe this is because I can hear it click when I switch the ignition on. One thing that I noticed is the currently installed valve clicks very fast and I am thinking that it could be something in the PWM setup in the ECU causing this. Both the tuner and I could hear it and it is somewhat intermittent, but like I said it performed great on the dyno, after we worked through some different problems.

nonvtecallmotor

If the car wasnt driven on the street after the dyno tune I'd say its too rich. Street driving and the dyno are two different worlds.

Bailhatch

No it doesn't.

Read your thread and check out all those things instead of hoping it's the solenoid.

If I were you, I would just throw a manual boost controler on there and keep turning it up until the problem comes back (boost cut, ignition break up, vtec, headgasket etc.). Then fix it.

96halx

From reading another post just now, and don't bite my head off if it's dumb, but could it be that the spark is having trouble igniting the mixture? (I just ask because it went away with lower boost pressure)

13173

I took it up the street and mashed on it 1-2 gear. Thats all I was able to do.....

I do not have a manual boost controller, nor do I live near anyone that has one to my knowledge. Its my own fault, but I can not remember what my boost cut is set at right now. I am waiting on my tune to be emailed to me. What if I am right, what if its the PWM circuit in the ECU or the solenoid itself? I have had ignition break up before on another turbo car and it was nothing like what I have going on now.

That could be the problem, but why wouldnt it do it @ 14psi and 16psi. I have had a car that was turbo'd and in the beginning it had ignition problems. That misfire was nothing like this misfire.