I'm trying to figure out if my sensor is bad. Is it true that under boost you should be able to see the volt meter move if the map is working correctly? I cannot see mine move at all. I tried unplugging it today to see what it did and I couldnt tell a difference in the way the truck ran at all other than it wouldnt build more that 10lbs of boost. I drove it for about 10 miles like this. The truck didnt smoke at all and never got a CEL. I have had the truck for about 2 months now and it has always been sluggish and terrible mileage. 9.5 to 10 if I'm lucky. Any info will be greatly appreciated.
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98 24V 3500 Flatbed 4x4. HotRod pump, Airdog and crappy mpg's

 

What problem are you trying to fix? You may have a boost leak. My volt meter is pretty solid. Grid heaters is the most noticeable thing pulling it down. All else is very minor & not really noticeable.

 

No, you wont be able to see the volt meter in the dash move. What you probably heard was that you can test the MAP sensor with a volt meter tester and if the MAP sensor is working then the volts will vary depending on specific readings. Although, you also should have immediately thrown a code by driving with it unplugged. Are you sure you didn't? How did you check for codes? Also, give as much history about your truck. Something may be obvious as to why you're not getting better fuel mileage.

 

It didnt throw on the CEL. It might have an internal code but I have no way of checking it. I bought the truck a couple months ago and has always felt slugish. From what I was told it has a new hotrod pump and airdog. I already replaced the filters thinking maybe they were clogged but that didnt change anything. It is on 285's which I know isnt the best but it still shouldnt be this bad. Like I said before when I unplugged it and took it for a spin I couldnt tell any difference in driving it normally. When I tried stepping into it some it just struggled to hit 10lbs of boost and wouldnt go any higher even with my foot to the floor. With the map plugged in it will hit 30lbs but doesnt feel like its really going anywere. There is no tuner in it as far as i know. I also pulled the MAP and IAT and cleaned them but they looked really clean already.

 

You should fill out your signature.

Is it an automatic? Does the engine sound like its working hard but the trucks just not moving like you think it should?

 

I did. Its in my first post but not the other for some reason. Yes its an auto. I forgot it has a suncoast tranny and converter. Doesnt really sound like its working hard. Just real sluggish on the bottom and doesnt pull hard in the higher rpm. Not that I've had it real high. Maybe 2500rpms.

 

Well my thinking is that it was the tranny/converter not transmitting the power to the ground. Especially if the converter isn't locking. But yours isn't stock. Your boost sounds good and I'm assuming that the fuel pressure is fine too. If you're not happy about the upper RPM power then I think that some of the new boxes add considerable fueling at the upper ranges or you can get larger injectors. You must have a box. Which one do you have?

 

It doesnt have anything that I know of. There is nothing visual hooked up and I havent put anything on it yet.

 

Thats strange.....well maybe not. You should look for any codes because if your reaching 30 psi of boost with no box or boost fooler than you have to be setting the "over boost" code which will send the VP into limp mode and defuel. Maybe thats your problem. But then again.....you shouldn't be reaching 30 psi during limp mode either. You obviously bought the truck used and from someone who modified it too. Do you know any more history of what the PO did to the truck? Maybe the wastegate was tampered with to achieve more boost since you should be getting no more than about 19-20 psi on a stock truck and I dont think the hotrod VP adds enough fuel to add that much boost either.
On another note. Since you dont seem to have a timing/fueling box, if you do add a mild box like an Edge EZ, that will definitely wake up your truck. Even though its an additional 60 RWHP and 180 lbs of torque.....thats considered mild. Wakes up the bottom end and mid range a lot. There's boxes out there that add hundreds of HP, but they wreak havoc on drivetrain parts.

 

what's your location?

 

It is possible that the CEL bulb is burnt out, mine is and will be as long as I own this truck. You might want to run by auto zone and check for possible codes.

 

I'm in central florida. I know the cel bulb isnt out cause it came on right after I bought the truck do to low apps voltage. Fixed it and cel shut off.

 

That doesnt mean its not bad now. But no matter, you need to have someone check if you have any codes.

 

Yes I agree on the codes. The CEL lights up everytime the key is turned on and then shuts off like all the other lights when the truck is started.

 

Well, it was just a thought.