New guy with low boost presure

[aj neireiter]

The SES light has a mind of its own. The guys at the shop said that the boost presure was to low, so they changed out the wastegate solenoid. That seem to fix things for a few months. The light still comes and goes and still reads the same code not enough boost presure! HELP!!!!!
ps... we also instaled a new vac. pump

[patrick m.]

check for vac at the actuator, also the plastic vac tubes often crack, inspect closely.
with the eng off, vac hose off, check the movement of the watesgate arm, it should move freely.
dont overlook a dirty air filter

good luck.

[LilRed Turbo]

Has anyone put a boost gauge on to verify that the computer is recieving correct data? Second have the vaccum lines been checked for leaks or replaced?

[DickWells]

aj: Was it code 78? (Wastegate solenoid fault) If it is the solenoid, you may be able to run without it. I simply jumped mine with a piece of neoprene hose. I pulled the little plastic connecter out of the solenoid body and connected the two little male fittings together. However, I have John K's boost control in my rig, so that might make a difference. I typically run at around 5lbs of boost at 60mph while towing. I go as high as 14-15 at WOT on a steep climb. I have to watch my EGTs, but the IC and good boost almost always keep these EGTs down low. Sorry for all the accronims if you're new to this game.
Oh. By the way. I went through two new solenoids before I gave up trying to run with it hooked up.
I get a code 78 all the time, of course.
Good luck, Dick Wells

[moondoggie]

Good Day!

You might want to look at Wastegate Solenoid Question (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=005667#000005) (click in the colored text).

Dick Wells said,

[gmctd]

There is actually no code for Low Boost Pressure.
A code set for Boost Sensor Low indicates a problem with the sensor and\or wiring, as in the connector is unplugged, or dirty, etc.
Or, the sensor has actually failed.

The code sets when the PCM sees that input as unreliable.

Same with Boost Sensor High - input is unreliable from similar causes.

Boost System Performance and Wastegate Solenoid Control alarms together can mean Boost is too high for desired conditions.

Boost System Performance alarm alone can indicate low Boost.

As stated above, specific DTC-#'s should be posted, and vehicle info for OBD-I or OBD-II specifics.

[DickWells]

Moondogie is right of course. You need a good cool blast of air through your intake, (intercooler) to keep things safe. However, the only times I ever saw my EGT (exhaust gas temp.) shoot up was when I lost my boost. I used to have to back off the throttle and come back on it to force a downshift, get my boost back and then my EGT's would plummet back down.
You need a gage to tell you where the EGT,s are. I ran a long way without my waste gate solenoid before I ever put in my intercooler. No problems. But, I did have the Kennedy boost control in place. I had it adjusted to give about 10 PSI max. back then. I had my 3 gages in from the time I put the Banks system in. For what it's worth, I seldom get above 170 deg. F in the transmission unless I'm pulling hard and long up a mountain out west in the heat. Then, I have never seen more than 220.
You're getting a lot of value from these other long term DP contributers. Stick with them and you'll get to love this page. I have.
Dick Wells

[Marty Lau]

I second getting a waste gate controller, either from JK or Heath they both great guys with ALOT of knowlege they will share for just asking.

[lupey6.5]

i had the same problem on my 94. it ended up being that at some point when the dealer was diagnosing a problem in the past they hand cut test notches into the wires going to the wastegate sol. these were not sealed well and the exposed wire corroded i had to cut mine and reconnect them with good copper contact then liquid electrical tape. good luck. just may have happend to you too!