Popping on boost

[reed4rmk]

For all of you with turbo experiance I could use some info. I have on 07 Apex with the Boondocker GT-25 side exhaust. First my PL Box went bad and then some other stuff. Got everything replaced and the dealer tuned it, took it up on the mountain and said that it was running great at 12 #s of boost and 12.5 O2. I took it up on the mountain and it seemed to be running good until I started climbing and when it started to get to 2/3 throttle it started to pop pretty badly and the more throttle I gave it the worse it got. It seemed like the more runs I did, the better it started to run. The next day I had to start the process all over. I should mention that when it would start to pop the O2 was around 11.5 to 11.7 so I don't think it's running to lean. This is on 50/50 race fuel with no other mods. WTF is going on and how do I get it to run consistently??? Thanks for your help.

 

[Linc]

Check your fuel pressure,also check your RPM it could bouncing off the rev limiter.

 

[reed4rmk]

Thanks Linc, RPM seems ok. If fuel pressure was low, wouldn't it be running lean and showing higher numbers on O2 guage?

 

[JSCC]

Popping is usually lean. Try adding more fuel just to make sure.

 

[Rioplay]

Try checking all your hose clamps to make sure you don't have an air leak from the turbo into your engine. If it happens when boost builds pressure that is probably your problem.

 

[#1Leaddog]

popping

They will start to pop at 11.7 and above. Needs more fuel.

 

[fastgas]

You're either hitting the rev limiter (often the tach can't keep up with the engine), maybe on the rich side, or you need to replace spark plugs (be sure to gap them down to 18-20 thousandths). The lead in the race gas knocks them out eventually.

 

[Duke]

Change Spark Plugs, had the same trouble a couple of weekends ago. Were you running Super rich after the Pure Tragic Box went

 

[Pastor]

We had one doing this the other day and changed the plugs and it cured it.

Problem was one of the plugs welded inside the plug socket and it was a real difficult thing to remove. Finally I unhooked the electrical and just turned the rubber piece until the rod in the plug broke.

We were real careful on the gapping 20 thousandths and the sled is running great now.

This was after we eliminated the normal problems that cause popping: over revving, too lean, too rich, under revving, (I have actually had popping because I was not revving over 9500 rpm WOT).

 

[reed4rmk]

Thanks guys, I would have never suspected the plugs. It was running super rich before I switched the box so that might have killed the plugs in the process. It's been checked by myself and the mechanic for air leaks so I don't think that is the problem.

 

[Pastor]

What did you figure out?

 

[The Predator]

They will start to pop at 11.7 and above. Needs more fuel.

not true...we have seen the best hp increase at 13.1:1 on the dyno and the hill... my guess is changing the plugs will fix it. I have seen that time and time again on boosted apexs.

 

[catman 1200]

not true...we have seen the best hp increase at 13.1:1 on the dyno and the hill... my guess is changing the plugs will fix it. I have seen that time and time again on boosted apexs.

dang aint that to lean 13.1

 

[reed4rmk]

Thanks FASTGAS, I had never heard of gapping the plugs like that since that was less than the yamaha stock specs. Looking up on the net I see where with a turbo...as the horsepower increases, the gap decreases by about .oo4 per 50 hp increase. Is this common knowledge? Do you think my dealer did that when he installed the turbo? Here is the big question...how do you get the caps off the plugs? I've got the bolt out but it's not coming off and I don't want to pry too hard and break something

 

[Snoboner]

Make a 1/4 turn and off she comes

 

[#1Leaddog]

Popping

It must have something to do with the gauge or the location of the sensor. On my sled and several others here 13.1 is way lean. On wide open boost I need to be 11.6/11.7.

 

[reed4rmk]

Got the plugs out, they were not in the best of shape. Noticed that they were all gapped at about .030. If a dealer is installing a turbo for you, isn't that something they would have changed at that time. Pretty sure they were the same plugs that were in it when I bought it. Sled only has about 1100 miles on it, 500 since the turbo. Especially sincie I've been complaining that it wouldn't run at full boost. I even took it in to them to check everything and test-ride it in the mountains..for which they charged me another $380.00 including miliage for them to drive it up, ride it, and bring it back. I'll test it Sunday and if it was the plugs I'm going to be a little pissed at the dealer.

 

[reed4rmk]

any opinions?

 

[savedbygrace]

I am assuming that the plugs did not fix your problem…?... Have you checked your TPS (throttle position sensor)? You can do this through your stock gauge pod in diagnostic mode. Not sure…but I believe it is d2. The TPS should read 14-16 at idle position, 95 at full throttle position and the numbers should move up smoothly as you open the throttle. The Apexs are notorious for TPS failures, this can cause your seld to run rich or lean depending on how the TPS fails…hope this helps…
Junior

 

[reed4rmk]

Ok, for those that want to know. After changing and gapping the plugs to .020, took it up on the mountain and it worked great. Full power at 12#s of boost, nice and smooth. Now my question is what do I say to my dealer? Should a reputable dealer that has lots of turbo experiencing, and is often recommended for people looking to put a turbo on, have taken the plugs and re-gapped them from stock when doing the install. I'm kind of pissed as I wasted most of the season working with him to get it to run. He also charged me over $300.00 when I brought it back to him to fix. When I picked it up from him he told me that it was running great, I rode it the same day and it was doing the same thing as when I took it in. Any ideas?