Engine/Transmission (1998.5 - 2002) extreme turbo lag????

[swampjeep]

Hello All,

I'm having extreme turbo lag, hoping someone here can shed some light, I'll try telling all I can abou tthe truck along with what it's doing.



I have a TST power box II on my 1999.

have had a problem before with a loose wire causing no turbo, but I've fixed that with no more problems there, also I guess I have a bad speed sensor cause my speedo only works above 50 mph, but this has been happening without the turbo lag problem.



The big problem now is this, I leave a dead stop and I can count slowly to 3, watching the boost climb ever so slowly, 2, 3, 4, then it takes off great. Sometimes even when up to speed, back off, then hit the throttle, there is the big lag again, or should I say it's probably always there, just don't always notice it always.



I really don't think the speed sensor is the problem cause that went out 6 months ago, this lag problem just started.



Please any help would be great.



Thanks

 

[JHudson]

Sounds like your map sensor has gone south. If it doesn't have the correct voltage, it will not fuel, or there will be a lag. Same thing happened to my 99, and the map sensor was the problem.

 

[swampjeep]

did it trip any codes? my check engine light has not come on at all since this has started.

 

[59Turbo]

If the MAP voltage isn't out of range then it normally won't set a code.

 

[Todd T]

sounds more like a dead pedal symptom possibly leading to the injection pump. does it do this every time, when cold, when hot etc?

 

[JHudson]

When my map sensor went, it set no codes or tripped the check engine light. The sensor at idle didn't have the correct voltage thereby thinking there was no boost and in turn didn't fuel until later with more RPMs. What I did was to take the sensor out and slightly bend the internal plate so the map thinks it has enough boost to fuel. Only slightly bend this plate or as another option just replace it with a new one. I run the blue chip FMS so it is very easy to see the effects of the map sensor with the boost guage in the FMS. Before I did this, the lag was huge, once the RPMs came up truck was fine. The only issue I have now is that on the FMS boost guage at idle it indicates . 5 - 1 pound of boost. On my other boost guage, the one on the air horn, read zero. Truck has been running this way now for 3 years with no lag at all. Maybe some day I will replace the map so the FMS boost guage read correctly again at idle, but that is $90. 00 from the dealer.

 

[swampjeep]

thanks for the info guys, right now I'm thining it's a bad Power Max2 computer or loose wire, I pulled the Power MAx2 out of the system and it is working like a stocker should, haven't checked the connections but I'll do that and plug it back in, stock just isn't good enough once you're used to the extra power LOL

 

[StevenP]

I just picked up a new map sensor for my 2000. I noticed a few changes from the old sensor. The length of the sensor and the orfice (if I can call it that) size changed. It was smaller too. My old p/n was 3348747 to the new p/n 4921497. Cross checked the numbers to make sure it was correct and it was. From Cummins $47. 78 with tax.

Steve