Engine/Transmission (1998.5 - 2002) low boost

[TWood]

I have a 99 4x4 with auto trans. All stock, added quadzilla scout for monitoring. The truck will only make 7 psi boost max. cruising on freeway it is usually zero and egt is around 600-700. It blows no smoke at all. I checked intake system for leaks and tightend a couple of the clamps that were leaking. I checked the wastegate and it seems to be working properly. I replaced the map sensor and still low boost. Also there are no codes. I've searched the forums and can't find a solution. Any help would be greatly appreciated

 

[DIESELWRKS]

when you put in on a load and try to make boost are you hearing any noticable swoosh sound or odd sound. like you already have done. check your complete are path. you may look up on threads on how to make your homemade pressure tester this will check for leaks from the turbo through your intercooler and to the intake. other than that I would say time to look into your turbo. on stock you should be making if remember around 19-20 stock. more people should chime in on this let us know what you find out. good luck.

 

[kccoon]

I would agree to check your intercooler because i have a 99 4x4 auto with a edge comp box and with the pickup set stock i can make 20 if i get on it hard and if i have the edge on i can make 26 on a good day and when im cruising down the freeway at 75 im makin 8-10 with the cruise set.
good luck

 

[Joe Mc]

Check to see if you have any pre-turbo exhaust leaks. If you're not getting all the exhaust gasses to the waste side wheel it won't spin up as it should and then the charge side will be lower = low boost. But, only 7# sounds real low, Is the IAT sensor clean or defective? Do a search for "IAT" and I'm sure you'll find plenty of info how to clean it and what are the correct ohms for a properly operating unit.

If you had a charge air/boost leak you'd be puffing some smoke, is the gage functioning properly or is there a hole in the gage hose? Is it running fine or seem like there's a loss of power?

 

[TWood]

I have made a fitting and checked the system for leaks. I have only had the truck for about 5 months and it seems to have good power but I don't have anything to compare it to. The guage seems to be fine, no holes. The guage also matches pretty close to the quadzilla scout monitor. I have not heard any whoosh sound or anything that would make me think there is a problem under the hood. I have cleaned the IAT and the scout also seems to be getting an accurate reading for the IAT. At start up the IAT reading is real close to ambient and climbs as the engine temps climb. I have not checked the exhaust but I will. one question for the exhaust. The tailpipe from the muffler back looks like it has been replaced and it is only 3 inch. could this cause some of my problem?



One question on the intake pressure testing. I can pressure it up to about 25 and it bleeds off fairly quick. To check for leaks I left my air valve on my fitting open a little the entire time. I know some of the air was bleading out the small hole in the elbow fitting for the wastegate hose. Was the rest of this air going inso the engine through the open intake valves ?

 

[DIESELWRKS]

just a thought were are you ported in to get your boost reading for your gauge. have you checked the connection on this also. as said before 7psi on a truck would be really weak and smokey. I cant help you on the waste gate issue I have never had any problems with my phat shat turbo and to be honest never had to take apart a turbo yet to give you advice on the turbo stuff. good luck