North American Turbocoupe Organization



Cant build boost
jaa55 Offline
Junior Member
#1
Im not positive of what my problem is, at first I thought it was my boost controller. My car started to build boost and would instantly "pop off". then I would not be able to build boost again until i got completely off the throttle. So I disconnected all vacuum lines to my wastegate actuator, I should be able to over boost now correct? It did the exact same thing. So now I have it wired shut but I havent got to drive it yet. the actuator feels like it has a lot of spring pressure. Something else I considered was a bad spring in the EGR. Any suggestions?
Reply

Pete D Offline
Administrator
#2
You may be opening up a crack in the IC hoses or one of them may be off location. Take them off and squeeze them to open up cracks. If you find any replace the hose. This would be one reason you could not build boos even with the WGA disconnected
Also start checking any vacuum hoses that see boost for spits and cracks. Many vacuum hoses do see boost

There should be a lot of resistance to pulling the WGA rod toward the WG.
Pete Dunham


Reply

jaa55 Offline
Junior Member
#3
ok well theres more stuff that may be related to the issue.....it "seemed" like the boost was building and blowing off. but now the car will not stay running. it will start up like normal and just shut down. I can still here the fuel pump run during all of this and I have spark the entire time. If I do get it to start I have to hold it at a very fast idle around 3k and it misses and runs very rich.

Ive went through unplugging every sensor and nothing seems work, Ive swapped the computer and VAM to another car I have and it works perfectly on it. I had a similar problem in a car before and it ended up being an injector shorted out internally but im fishing for ideas here.
Reply

Tbird-fanatic Offline
Senior Member
#4
Have you checked the intercooler boots. They can cause exactly the same problems.
1988 Tbird TC - in pieces - barn find - mods beginning while restoring
2000 F250SD XLT CCSB 7.3 Powerstoke - Daily Driver - AFE intake, Swamps tunes, straight piped
Reply

jaa55 Offline
Junior Member
#5
yes, all the clamps and boots are brand new. it has a FMI. when I get it started once it warms up a bit it will stay running but still misfires
Reply

Kev Offline
Posting Freak
#6
I would pressurize the intake and check for leaks. I'm with the other guys that say it sounds like a boot is off somewhere. ESPECIALLY if all the boots and clamps are brand new. That means you've messed with them recently, and I bet when you find it, you'll feel dumb. Experience talking there. Big Grin
Kev
1988 TC 5spd
Reply

Pete D Offline
Administrator
#7
Include cheking to see if the VAM hose slipped off the back of the VAM, like of the bottom, out of sight. Easy to do because the clamping area is so narrow.
Pete Dunham


Reply

jaa55 Offline
Junior Member
#8
Ok checked all my connections, I have two unrelated problems. One of the intercooler pipes came loose which was causing my rich/no start problem. I checked every connection including VAM connections, all is very tight now. Thanks for all who suggested this.

I still cant build boost...it runs great...starts to spool and pops off again. it happens around 3500 rpm at WOT..After it happens the engine will bog, like whatever let the boost go is still open. Only when I get completely get back off the throttle can I get back into it and build boost again. I took a check valve and ran it to the vacuum tree and to the EGR valve to hold boost on the pancake inside. It modified the problem a bit...next step is blocking it off.

it runs completely normal now otherwise.
Reply

Pete D Offline
Administrator
#9
How much boost does it build before it pops off and does it always pop off at the same boost level?

When it bogs and you lift off, can you get right back on it or does the engine run rough for several seconds?

Have you tried making and using a pressure tester. See this article and the pictures I posted in it about 1/2 down the page:
http://natomessageboard.com/ultimatebb.p...692#000001
Pete Dunham


Reply

Tbird-fanatic Offline
Senior Member
#10
I maybe totally off and youve already checked this, but never hurts to bring it up to rule 1 more thing out for the thinkers. Did you check the manifold to turbo gasket?
1988 Tbird TC - in pieces - barn find - mods beginning while restoring
2000 F250SD XLT CCSB 7.3 Powerstoke - Daily Driver - AFE intake, Swamps tunes, straight piped
Reply





Users browsing this thread:
1 Guest(s)



Theme © iAndrew 2018 - Software MyBB