Mike S

I have a hesitation or almost like a defueling issue between 27 and 2800rpm; what my truck does is it pulls exceptionally hard up to 2700rpm range than it feels like it defuels and than picks back up again, rail pressure stays solid right at 22500psi so I am pretty sure my fass is keeping up, boost holds at about 50psi. So what do you guy's think can a map sensor be the culprit?? Thanks for any help, Mike

AK RAM

Funny this came up again. I have the same thing as does Tommygun and SRadke on TDR and I JUST (like 5 minutes ago) got back from the dealer having them check a few things out. APPS signal is all over the place, but it only seems to act up when the TST is on. Turn everything off and it is relatively steady. They say the APPS is fine and is not the cause. The boost reading that the ECM reports is all over the place as well. When I'm at cruise at 8 lbs of boost, the DRB says the ECM is reporting 24 lbs of boost. During acceleration at say 25 lbs of boost, the ECM is reporting 35lbs of boost. At idle, it would show no boost, then all the sudden report 18 lbs of boost all on its own for no reason. Now, I have set over boost codes before at 29 actual lbs of boost, so I would think the box doing boost fooling would not let the ECM see that much. Well, the ECM is reporting 35lbs whether it is actually seeing it or not I don’t know, even though it is wrong, yet not throwing a code. Weird. I ordered a new MAP sensor just for giggles. I sure would like to figure this one out. Your truck is the first 04 I have seen with the problem.

CrashCade

Last time I took my truck in for service, they told me that they were seeing 11-14psi more than my gauges were showing. It sounds like it is along the same line as what you are seeing AK. The Tech there was not exactely sure what would cause that as there were no codes at all in the computer. They gave me my truck back as I did not have any issues to make them look into it any further. I guess I could take it back and let them figure it out, or atleast try. Since my truck is there right now, I guess I could have them check into it as that might be the source of some of my other problems.

AK RAM

What other problems are you having?

CrashCade

I get some excessive smoke when under accelleration, not WOT, but normal acceleration. I guess mine kinda falls on its face around the same time. I really notice in gears 2 & 3. I just never thought anything about it till this thread. I also am not seeing the gas mileage I used to see which started around the time it started smoking more. Also have seen higher EGT's but I also had my intercooler replaced because the other one blew. I just figured it all had to do with the intercooler, and maybe less flow, but that does not make sense since it is the same type intercooler.

CrashCade

I just found this on TDR.

"As for more smoke with a laggier turbo, not really. The computers in these things fuel based on how much boost they see. If you're not making boost, you don't get the fuel. That's why they run so clean."

Is this true? Is this why I am seeing smoke do you think? The ECM thinks it is getting more boost than it actually is and dumping more fuel?

Mike S

Well Mark at TST was thinking that this could cause it so I thought that I would just throw it out and see what you guy's thought before I go and spend $70 on a new Map sensor, but thanks for the reply's. So today I am having one of those good TST day's and since today is test and tune up at Bandemere Speedway I am going to take her out for the 1st time with these twins, injectors and all these other new goodies and see what she will do in the 1/4. Mike

AK RAM

Outstanding! Let us know what you run!

Seems I remember you having an SO engine.

I already ordered a new MAP and it should be here on Monday or Tuesday. I'll post if it helps.

Mike S

No I have a HO & please let me know if that new sensor helps. Thanks, Mike