Engine/Transmission (1998.5 - 2002) Verry laggy boost, decreased overall boost?

[runningbird]

In about a period of a week my truck has lost a lot of power, especially from a stop. Full throttle from a stop results in an extreamly slow boost reponce maxing out at 20psi in 1st, and only creeping to 25 in 2nd where as it usualy will jump right to 28psi. Flooring it at any speed results in a verry slow boost responce, and doesn't do any better when the converter has locked. Engine mods are dd2's and and edge ez(boost elbow). Anything I should check? I wouldn't think that the wastegate flapper could collect enough carbon to be doing this in the period of a week.

 

[klaybus]

Boost Leak

Check your boots! Especially the boost boot right off the compressor. How are your EGT's? When I ran II's, I had a heck of a time with that 1st boot off the turbo.



Clay

 

[LOtero]

boots boots boots!! i blew the one off right off the cooler, and could hardly tell, check em all the way around, mine just came off a lil on the bottom, watch those egts!

 

[OPoole]

Check the 2 lower boots the fenders will rub holes in them.

 

[runningbird]

All the boots are intact and fastened correctly. At full throttle in 3rd gear boost will make it to 25-26 psi in the lower rpms but fall to 20 before it shifts to 4th and the boost returns to 25ish. Maybe not getting enough fuel either? Feels like a real turd.

 

[GarrettPetersen]

do you have a exhaust brake on your truck by any chance

 

[runningbird]

I do not have an exhaust brake.

 

[TMWeber]

I also suspect boots. A visual inspection doesn't always reveal a bad spot. Try pressurizing the system and spraying all connections and boots from the turbo to the intake manifold with soapy water. (Remember to check the boost gauge line and fittings too). Sometimes the boots have to be taken off and sort of bent and streched and flexed to see if there is a crack and even then it can be difficult to se them. I did this on my first gen and they all seemed good, but when I pressurized the system and sprayed soapy water on the boots, there were leaks that I could not see. before. I was having similar symptoms as your describing, I had to hammer it hard in fourth to get boost to 20 lbs and if I let off slightly boost would drop - not decrease like it does now - but drop! Anyway, changed the boots and HUGE difference. Good luck.

 

[TowPro]

I had one start popping off on my 98. 5. It was the inlet side of the intercooler that used to act up, very hard to see, the rubber would actualy pull out from under the clamp in one small area that was hard to see. Someone on here send me a set of boots off a 2000 truck, they are about 3/4" longer then the 98. 5's were. Never had another problem after that.

 

[RacinDuallie]

Best bet really would be to pressurize the system starting from the outlet side, to make things easier, get a hard rubber plumbing cap and seal in an air valve, disconnect the intake horn boot and remove the boot from the intercooler outlet pipe, install cap and pressurize system to about 35lbs. and start searching, check all connections and even check across the entire intercooler... . I would even check the bolts holding the cases together on the turbo... . And for kicks, check the condition of the tubing and the connections to your boost gauge. Snug down the intake horn bolts and even check the intake plenum coverplate bolts. Also look around the head gasket area for leaks... Check the wastegate supply hose- is it kinked?

You have to start with supplying pressure into the sytem and begin your search.

 

[BPonci]

Supply and demand. Check your fuel pressure at wot. Sounds like your fuel pressure is ok in the lower rpms but at the high end it may run low. BTW hows you pyro temps? Up or down? If its down and boost is down it very well maybe a fuel issue. Hope you find your issue.

 

[runningbird]

Fuel pressure at wot dips to 6-8ish, and egts are not an issue, never over 1000. I will check the system for leaks... but I am leaning twards fuel. In the moring fuel pressure is only 10psi (45degrees outside), as apossed to normaly 13 or so, is this normal?

 

[ddunk]

I had the same problem. It turned out to be a bad connection at the map sensor. I also got code p217. It was caused by the edge comp harness looping the map signal(bad connector)had to replace edge harness

 

[runningbird]

is that an overboost code? I have a problem with overboost every 2 months or so which results in the a/c not working.

 

[ddunk]

I might be wrong on the code number. It was low voltage to map sensor circuit. I would unhook your edge box and run it stock and see how it runs

 

[Holzarbeiter]

Check the hose going to the wastegate, a friend of mine had the same symptons, boost below normal and was missing power, turned out the hose to the wastegate was shot