Throttle cut out under boost, now it won't start

texFCturboII · 08-28-07, 01:35 PM

Ok, So I was driving very aggressively the other night; running with some motorcycles, doing about 135 @ 5000rpm's in 5th. Suddenly the throttle cut out, meaning that if I hit the gas at all it just bogged up and wouldn't accelerate, without the throttle it just decelerated like normal. So I limped over to the side of the road to try to restart it. ( I thought I had just gone into limp mode maybe?) But now it doesn't start.... correction... it starts but it is just a quick start: she turns over and starts but then immediately dies. I can't even give it gas to rev it up. I popped the hood and with my trusty flashlight gave the engine a quick look over. As far as I could see being dark and having a crappy flashlight, vac lines were good. My next thought was the throttle... and there it was, one of the throttle cables seemed to have become unseated. After some fighting with a hot manifold i finally got the cable re-seated but the damn thing still does these quick starts and won't hold an idle. I did some searching and have come up with three (albeit somewhat ignorant) ideas: (1) Vac line I'm not seeing somewhere, (2) Intercooler coupling popped off (3) Something bad with the throttle body (4) AFM (5) Blew the engine

School just started again so I haven't had time really look into these, just trying to get an idea of what to look for when I do get to check it out.
Any other ideas?

1989 Turbo II
Mods:
FMIC
720cc secondaries
Walbro 255
no power steering
no A/C
no smog pump
all emissions removed
3" downpipe
S-AFC II
Greddy Boost Controller
PYX Wideband

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gxl90rx7 · 08-28-07, 04:19 PM

sounds like a vacuum leak to me. check intercooler piping for cracks and all your vacuum lines near the TB to see if any popped off

couldnt hurt to check compression while youre at it

USS CJ · 08-28-07, 04:23 PM

this same thing happened to me at the track once, just check all your connections and make sure you have vac leaks.

texFCturboII · 08-28-07, 04:26 PM

thanks for the confirmations, will post up tomorrow with results...

boost_its_what_for_dinner · 08-28-07, 08:57 PM

how much boost? take a pic of engine if possible so we know what exactly it looks like.

veedubbed · 08-28-07, 09:22 PM

Sounds like you just blew off a vacuum line. Check the brake booster line on the back of the UIM, as well as the intercooler => throttle body hose. That one always liked to pop off on me under boost.

7dust · 08-28-07, 09:29 PM

My AFM plug has been known to wiggle just a little loose. Check yours.

arghx · 08-29-07, 12:01 AM

check AFM and check your intercooler piping

initial D is REAL! · 08-29-07, 12:10 AM

You getting fuel pressure? updates? Was it a vacuum line, or sensor dissconnected?

texFCturboII · 08-29-07, 12:42 AM

Haven't checked it yet, I've got class until tomorrow evening at which point i will roll it off the trailer and take another look at it. Boost- I was running 11lbs. boost on the stock turbo. My first thought is a loose line as well, so I will be meticulous. What threw me off though was the throttle cable! (I'm assuming it was a throttle cable.) First off I didn't know that we had two of them! Second, to get the cable to reseat I had to wrap the little ball at the end in electric tape; there was about a 1/4 of play in it.

Longshoe · 08-29-07, 09:22 AM

One of the cables belongs to the cruise control.

sharingan 19 · 08-30-07, 03:19 AM

^^^ Another pound or two that can be shed in the name of simplification and quicker ET's

I had a similar thing happen to me, and it was a IC pipe that had blown its way loose, just not completely off.

texFCturboII · 08-31-07, 09:21 PM

Ok, so checked it out today after classes and it looks like the IC piping is good, I replaced the AFM, and all the vac lines that I could really see were on. So tomorrow I guess I am going to take of the UIM and really get behind and see if there are lines that I am missing just hanging about. Any pointers when taking off the UIM?

sharingan 19 · 09-01-07, 12:38 AM

disconnect the throttle cable, its a pain to have to find some place to sit the UIM w/o putting kinds int he cable or it getting in the way.

texFCturboII · 09-01-07, 10:17 PM

Woo Hoo!! Ok, so i got the UIM off and checked all the vac lines, everything was good (as it should be, they are all brand new). As i went to put back on the intercooler to intake pipe I noticed that one of the pipes had blown loose. Ya'll were correct, it was just a pipe from the intercooler. She started up and runs just fine, thanks for the help peeps!