I have another thread on this engine swap that I'll link at the end but it's really more in the troubleshooting phase now and this area might be more appropriate. This is the US 1.6 ECOTEC drive-by-wire engine with coil on plug ignition.


Long story short, my friend's Aveo had the engine die due to overheating so I found her a 60,000mi used engine and installed it. It won't idle but runs fine if I can get the RPMs over 3000. At high revs the engine responds normally to the throttle but at lower than 3,000 it does not and giving it gas tends to kill it.

When you crank and start it revs to 2,500 then drops down to around 500, goes back to 2,000 and then back below 1,000 where it's missing and running rough then dies out. This happens consistently and if I can catch it and get it over 3k it responds to throttle normally consistently too. I have used both coil packs and both sets of plugs with no difference.

I've run it through three heat cycles now and it's throwing no active or pending DTC's. I'd try the non-GM scan tool learning procedure but it won't idle. I did try running it at 3,500 for 180 seconds and then shutting it off for 60 seconds but there was no difference in low speed operation.

I'm not really good with DBW throttles, don't like them and never had to troubleshoot one before but I thought maybe I had a bad throttle unit on the new engine based on readings so I hooked up the old throttle and got very similar numbers.

Is there a way to do diagnostics on the pedal assembly?

Here are the numbers I got with the designations from my HF scanner:

Engine Off Values, "new" throttle on engine

TP Closed - 27.2% WOT 39.6%
TP_R - 14.9% / 26.3%
TP_B - 28.6% / 39.6%
APP_D - 19.6% / 85.1%
APP_E - 9.8% / 42.4%
TAC_PCT 19.6% / 37.3%

"old" throttle connected to harness

TP Closed - 27.5% WOT 39.6%
TP_R - 14.5% / 26.3%
TP_B - 28.2% / 40.4%
APP_D - 19.6% / 85.1%
APP_E - 9.8% / 42.4%
TAC_PCT 19.2% / 37.3%

I had thought that maybe the new unit was bad and I'd see more matching values but since they're the almost the same with both units for now I'm assuming they are both good. The car drove to my house under it's own power with only a dying engine and I'm at a loss here. Any help appreciated.




(Engine swap thread, no real info there that isn't here.)
http://www.aveoforum.com/forum/f82/h...ne-swap-20408/