Stumped

larrym

West Coast Newfy
Joined
Jul 17, 2007
So had the car out testing the new seats got on it a bit when I was cruising back home noticed it was really lean and stumbling coming to a stop symptoms of a large vacuum leak drove home popped the hood and grabbed my stethoscope nothing obvious hmmm did a smoke test still nothing swapped the pcv no change. Compression test 5 at 150 # 5 at 135 that might account for the boost flutter. When you fire it up cold it fat idles good until it gets to temp then lean and rough. Tried another narrow band no change the part that really confused me is that there is very little change in the IAC it's right around 15 TPS is good too. My BLM has climbed from 120 at idle to 129.
 
Might sound stupid, but check your throttle body bolts. I had a rough lean idle warm and a weird sound under boost. Some how the TB bolts backed out a bit. Tightened them back up and all was good.
 
That was my first thought I blew out a dog house gasket same symptoms but there are no leaks to be found.
 
So I dumped a gallon of methyl hydrate in the tank no change put the vacuum gauge on and it reads about 12, blocked the TB and smoked it again a lot still no leak checked the sloop in my chain it's about 8 degrees I think it's time to put it on a stand and see what I can see
 
Ok here is an update. I pulled the motor found a leaky exhaust valve and took the head in and had it fixed explains the low compression on one hole,I also found a head gasket that I thought might be causing the problem. Put it all back together and still shitty idle. Resealed everything on the intake. Tried another MAF nope different computer nope different chip nope swapped fuel pumps nope swapped one of the LS coils out tested weak nope vacuum is up to 18 so that's better and I put 15 pounds of boost to it with no issue but something is not right.
ImageUploadedByTapatalk1467298552.965814.jpg
 
Last edited:
I have not measured it but visually everything looked good its a little roller cam, I swapped the chain while I had the motor out too. This came on suddenly I was driving and hard run it out tuning it was rolling to a stop on the way home low 02s and shitty idle figured I had pushed a plenum gasket out at first since I have done that before with similar symptoms
 
Ok I might have found something? I went to start it when it was cold. Start stall, start stall hmm identical symptom to when I forget to plug in the MAF. I unplug the GENll translator fire it up and away it goes idling like a champ throws a code for low MAF but that's to be expected. Checked all the wiring to the GENll it appears fine. Gonna see if I can borrow a regular translator and a chip to try see if that changes anything.
 
So swapped in my buddies translator and TT chip purred like a kitten....
BLM was good IAC was good.
Reinstalled mine and was reattaching it to the dash it dies. My buddy tugs on each wire on the connector and duplicates the symptom twice. Looks like I need the connector repined we tightened them as best we could with a pick but I'm going to get the pin tool and take it apart add new connectors on the plug see if that smartens it up.
 
Top