Yesterday i changed my belt from the stock 112" that comes with the Radix kit to a 110.5" Goodyear Gatorback. The steps i took to replace the belt are as follows: removed the air intake tube from the MAF to the Throttle body, then removed the top radiator shroud and then loosed the tensioner, then removed the belt. I then installed the new belt adjusted the tensioner, put the intake tube and radiator shroud back on. Started the truck, runs and idles good, did not immdialetly test drive it though. Went outside through the football around a little with some friends, then my buddy came over to show off his newly painted MR2. We then decided to go to Wendy's, hopped in the truck, and took off down the road.

Here's the issue, the truck starts, idles, and drives fine, UNTIL you try to put the truck under some significant load. Once you start to get into it, making about 5psi of boost, the engine starts to shutter/miss/vibrate/shake really bad, and the power seems to be missing as well. If you continue to stay in it, it will make boost fine, up to about 9psi, but the engine is shuttering/vibrating violently, but does continue to run. I let off the pedal immediatly, and the truck continues to run fine again. Now i'm like WTF!!!???

So, took the truck home pulled it in the garage and opened the hood, can't see ANYTHING out of the norm. First thing that came to everyones mind (since we had the intake off changing the belt) is a vacuum leak. So i took the intake back off, checked the line going from the intake tube to the intake, it is on good. Put the intake tube back on good and tight, took it for a test drive, still doing it.

Brought it back home, (really getting worried now), and starting back tracking all my steps on changing the belt.

Now, keep in mind, the truck ran fine all day prior to installing the new belt. This all started happening AFTER i changed the belt.

Figured, OK, maybe its the belt causing something crazy to happen, slipping of something (not likely at all, but i don't know what else to check at this point). So i took everything back apart, put the original 112" belt back on, and its still doing it. Took everything back apart AGAIN, and put the Gatorback on again. This time being VERY VERY attentive to EVERYTHING we were doing, making sure EVERYHTIHG is tight, etc. Still doing it

Next we start checking all other hoses, connections, etc. Checked all the spark plug wires, injector hookups, re-torqued the intake manifold (lol), pcv valve, MAF (took it off, verified all is good). I mean we stared at this engine bay for like 3 hours checking and rechecking everything we could get our hands on. Also, not getting ANY CEL's.

Now, about pissing my pants, i call up Bill (wkdivr), he comes over, hooks up his HPTuners to see if we can see any codes that might not have tripped the CEL. Not seeing any however. Started the truck with HPTuners logging on, and held the brake down, put it in Drive, then gave it gas until I could make the engine shutter. Then we looked the HPTuners log and compared it to one we did for my truck a few weeks ago. The only abnormal thing we were seeing is that the timing is all over the place. It dosn't look normal at all. I'll let Bill chime in and give more detail on that one. After seeing this, we decide to reprogram the pcm using the stock Radix tune (which is what has been in there working fine since the Radix install). PCM re-tune was successful, however that did not fix it.

Now we're at a loss, can't figure this out for the life of me. I'm sure that it's hard to completely understand the description of the problem from just reading what i've typed so far. The best way for me to explain it is to say it sounds/feels like maybe i'm dropping a cylinder or maybe two. Bill thinks it sounds/feels like i'm hitting my rev limiter. I hope that might help you guys better understand my problem.

Anybody have any ideas? i'll probably have to take it to my mechanic tomorrow to see what he thinks.

Bill, if i missed anything or you can elaborate more on this, please chime in.

 

you did not by any chance leave something in the inlet did you....i.e. rag or something like that.....

sounds to me like it might have ingested somthing....Just a thought at this point...I am thinkin of other possible problems.

 

The problem sounds to me like it's somehow ignition related. There's no vacum leaks under the hood, but standing near the tailpipe, you can really hear it. That what leads me to believe it's ignition, somehow. Maybe the coil pak or paks have gone bad.??? I watched the bypass valve when he brake-stalled it, and the problems come on when the bypass valve opens. I don't believe that to be the problem, but it comes on at that point of engine loading. Brian, if you're reading this, give me a call at 412-257-8086, Bill


Also, when he mentions retune, he means he uninstalled the Mag tune, then re-installed it. No a new, or aftermarket tune.

 

Maybe a damaged MAF. Use a Screwdriver to tap the maf while the truck is running and see if you get the problem.

Good Luck
CD

 

Just read your reply Bill, I am headed out for a bit and I will call you....how late is too late?

 

Have you checked all of your plug wires?

Just pulling **** out of a hat at this point.....Its so hard to trouble shoot without having the truck here.

 

Alright...as of 10AM Monday took the truck out, and romped on it enough to throw codes. Cyl 8 misfire. Looks like it time for plugs, and wires.

 

THERE IT IS!

 

I guess, concievably, you could just replace the one that's bad, but if it were me, I'd go with NGK tr6's, and maybe some good wires. Which seem to be the best wires?

 

how much exactly did we romp on it william? lol