I have had my truck for a few months now, and I have about 2300 miles on it at this point. I started moding the truck about a month ago, but I have had no problems at all up until now.

When driving normally, the truck starts to act funny when I decelerate. It is particularly bad when I let off the gas when coasting down a hill. When it starts to buck a little bit, I have thrown it into Neutral to see what happens. The revs drop, then rise for 1 second, then the truck stalls. If I leave it in drive, it will not stall, but it feels like it wants to.

I have heard that it could be the contacts on my chip aren't clean, so I checked that. I have cleaned it twice now, and it still continues to stall. I scratched the contacts, cleaned them over and over again, and even used official Loctite "electrical contact cleaner".

I have very few mods: chip, 4 lb pulley, ram air w/ filter, tr6's

Truck has been running great until 2 days ago when this started. What could this be??????????

 

Sounds like you may have fouled out a plug. Ask your tuner what he recommends for a plug with those mods. Try pulling a plug to see what it looks like. Does it only do this when cold, or does it do it all the time?

 

It has been cool and damp over the past few days when this started, so I can't say whether it does it when warm or not.

The plugs are brand new tr6's, but I guess I could have damaged one already. I did go to the track when it was about 35 degrees, and I did experience minor detonation on the top end that night. However, I have been running fine for the 2 weeks since.

 

I believe most guys would tell you that the TR6s are too 'hot' for a 4 lb pulley. The TR6s are just one step 'colder' than the OEMs.

Having said that, I don't think you are exibiting a plug problem as your truck is acting up witout a 'load' on the eng. It might be a TPS out of adjustment or an IAC that is carboned up as these both come into use upon deacceleration?

Dan

 

The other thing that I am confused with, is that it only stalls when I pop it into neutral right after I let off the gas. If I come to a light and put the truck in neutral, then it remains normal and does nothing.

 

Second thought: You may have a vacuum leak? Check your IAT sensor and the vacuum line on the bottom of the intake boot since you installed an intake kit. If not one of those, keep looking for a loose/open vacuum line.

Dan

 

What I meant was. Does it do it only in the first 5 minutes or all the time? If it's all the time then I would also tend to agree with the possibility of an air leak. I still highly recommend that you ask your tuner which plug to use. Exactly how does it act with load, no load, upon startup, excellerating at WOT, etc?

 

According to my brother-in-law (my own personal Ford certified mechanic) it sounds like my IAC motor has gone bad somehow. I am planning to take it by for him to look at it tomorrow, so I will find out then.

Thank god for having a "mod friendly" family member!!

 

Hey bud, let me know how it goes. I can help you get it straight man....

 

Well, my problem is apparently not related to the IAC like I thought. I had it replaced today, and it made no difference.

In an effort to troubleshoot, I plugged the boost bypass back in and removed my chip from the pcm.

The problem still persist. It is extremely evident in 3rd and 4th gear. You accelerate and let off, and it feels like someone is tapping the brake.

Scanned the computer, and no real codes popped up showing anything really wrong.

Has anyone experienced this? Is it possible that the chip (or something) screwed up the computer? Is this possibly transmission related?

 

If you want to meet up tonight, I will take a look at it. Email me if you do.

 

Your ABS may be screwed up???

Dan

 

My truck started doing a very similar thing when it started getting cold. I thought it might be the TPS voltage so I checked that (it wasn't the problem). I set the idel up and rechecked the TPS voltage and it still made no difference. Then I got a check engine light. In the end I took out the 160 degree thermostat I had installed and the filter I installed on the PCV line. The check engine light did not come back on and the engine idels properly now. I do not have a chip or pulley. I am going to get Autotap so I can chae it further later.

 

Since this effects the truck during coasting while in or out of gear it is hard to narrow down. I haven't done anything to the truck that differs from the normal mods, so I am somewhat confused.

My next idea is to re-adjust the boost actuator. I messed with it when I first bought the truck, and I finally got it exactly where I wanted. I have had it set that way for a while. However, it could have moved some, and thus may be affecting the idle speed.

We are going to replace the computer to see if that got messed up. I just figure we will keep replacing crap until we troubleshoot this.

 

Any chance the MAF could have gotten oil from the K&N on it? Maybe a vaccum leak, I have heard of the EGR tube touching the exhaust manifolds and failing?? Not sure why it only does it when at speed though, this makes me think it has something to do with the MAF. Check to see if the MAF is tight to your ram air box and no leaks. Hope you figure it out.