View Full Version : starts& runs,but no go.....

pro street rich
03-29-2004, 08:52 PM
Put a new engine in again, this one starts & runs at 650 rpm's. As soon as you give it some gas it either goes into boost and starts to die, or it comes up to 1500-2000 rpm's then falls off to 600 and comes right back up again. When it falls the boost goes to 5-8 lbs, and when it comes back to life it has 15-18 on the vaccumm.....
Checked the fuel pres, holds at 40 lbs, no matter if the engine is runnung or falling down.
Changed the "DIS" with a known good one, no help. To me it seems like it is either losing spark or fuel.
Put a light on all the wires, all show good...Everything is new on this one so now I am going crazy........
Any good ideas????? comments??????? or do I have to go and put another big block in this one too??????? One more thing, it is NOT kicking any codes either. How about it??......Rich

91 XR7
03-29-2004, 09:10 PM
Major Vacuum leak or Bad MAf sensors?

pro street rich
03-29-2004, 09:25 PM
Already went looking for the vacumm leak,sprayed all over the place and no increase on the rpm's... Will swap out the maf with a known good one next. Thanks for the idea, hope it works........Rich

91 XR7
03-29-2004, 09:47 PM
Some Vacuum leaks can be hard or impossible to find by spraying something around joints and such.. we had a 911 Engine that had a MAJOR Vacuum leak, Spray Ether(sp) and even propane around any intake joint/connection.. NO CHANGE at all.. finally took off the intake and noiced 2 intake gaskets MISSING after replaing all the intake gaskets (and adding the two that where missing) it ran like a champ :)

Not to say there is a Vacuum leak.. also could be the IAC..

03-31-2004, 12:13 PM
did you attach the ground strap on the back of the left head?

just wondering


pro street rich
03-31-2004, 01:52 PM
We hooked two if not three up, will have to look at that head to be sure. I did swap out the maf with a stock one and it did run better. On thursday I will get the chance to swap it for a known "good" one and also put my one on the other car and see if that helps even more. Thought I was good to go on this maf, as it was working fine on the last engine, maybe it got bangged or something while it was off the car for the transplant....will see on thursday night. I will post what happens so others can go with the info......Rich

03-31-2004, 03:49 PM
Mine did the same thing. I ordered 6 different mafs before I got one that would work. Hope you have better luck than me. But it definately sounds like the maf.

pro street rich
04-01-2004, 07:12 PM
Well it was the maf that was the trouble. It looked like something got sucked into the metering tube and was goofing up the deal. This was weird, as it was running just fine before the other engine broke. Don't know how it happened, as there is a filter on the system. Oh well, it's good now. Thanks for all the advice from you guys. ........Rich

91 XR7
04-01-2004, 09:21 PM
Glad to Hear you got it running...

Also whatever it was that was stuck in the MAF's passage may of gotten there when you had it removed, or the engine removed and was just laying in the tubing?? :confused:

now i'm wondering why my car was running as if NA 3.8L hualing a 10 tonne Anchor :eek: