jgouds
Proven Member
- 36
- 1
- Jun 2, 2014
-
Calgary,
AB, Canada
Hi all,
I've been dealing with a problem that I can't seem to get figured out. All the symptoms seem to be pointing to a vacuum leak, but I can't seem to find where the leak is coming from. All I've had at my disposal to find it is a can of carb cleaner and listening for idle changes (not the best, I know).
I've forced open loop on the car, so O2 sensor is not the culprit. Timing is good. Plugs and wires are only a couple months old.
The problem:
Can't seem to get the idle sorted. Timing set, then idle dialed in with the BISS. AFRs rock solid at 14.7, but only pulling 10inHG. Then I go for a drive and am idling at a light, idle is 700, AFRs are 16. Idle at a different light will be 1100 and AFRs will be around 12.
When I'm cruising the AFRs will be varying degrees of rich. Most cruising situations I'm sitting right at zero on the (aftermarket) boost/vac gauge.
When I get on boost, the transition between between vac to boost is bad - everything is very hesitant and AFRs are all over the place. Then after 5psi, car pulls and AFR's slightly rich.
What I've tried:
Replace gaskets/seals - throttle body gaskets, intake mani gasket, injectors upper and lower seals.
Looked for vac leaks with carb cleaner
Checked base ignition timing and mechanical timing
Car was idle surging when warmed up before idle and base timing were set - unplugged ISC and the surging stopped.
After idle and base timing were set there wasn't anymore surging. Unplugging the ISC made no change.
Engine management/gauges:
Moates Ostrich with Tunerpro RT
AEM UEGO wideband
Autometer boost gauge
Palm logger with MMCD. Outta batteries - will rectify and try and post a log
Relevant Mods:
EIII Big16G
FIC 550cc Injectors
3" GM Maf w/ MAFT
Larger cams (unknown brand or grind) think I have some pictures if someone thinks that's relevant
Apologies for the essay. Any insight into the problem would be appreciated. I haven't got a vacuum/boost leak tester available to me - so any ideas of diagnosing without one of those would be golden as well.
Thanks!
I've been dealing with a problem that I can't seem to get figured out. All the symptoms seem to be pointing to a vacuum leak, but I can't seem to find where the leak is coming from. All I've had at my disposal to find it is a can of carb cleaner and listening for idle changes (not the best, I know).
I've forced open loop on the car, so O2 sensor is not the culprit. Timing is good. Plugs and wires are only a couple months old.
The problem:
Can't seem to get the idle sorted. Timing set, then idle dialed in with the BISS. AFRs rock solid at 14.7, but only pulling 10inHG. Then I go for a drive and am idling at a light, idle is 700, AFRs are 16. Idle at a different light will be 1100 and AFRs will be around 12.
When I'm cruising the AFRs will be varying degrees of rich. Most cruising situations I'm sitting right at zero on the (aftermarket) boost/vac gauge.
When I get on boost, the transition between between vac to boost is bad - everything is very hesitant and AFRs are all over the place. Then after 5psi, car pulls and AFR's slightly rich.
What I've tried:
Replace gaskets/seals - throttle body gaskets, intake mani gasket, injectors upper and lower seals.
Looked for vac leaks with carb cleaner
Checked base ignition timing and mechanical timing
Car was idle surging when warmed up before idle and base timing were set - unplugged ISC and the surging stopped.
After idle and base timing were set there wasn't anymore surging. Unplugging the ISC made no change.
Engine management/gauges:
Moates Ostrich with Tunerpro RT
AEM UEGO wideband
Autometer boost gauge
Palm logger with MMCD. Outta batteries - will rectify and try and post a log
Relevant Mods:
EIII Big16G
FIC 550cc Injectors
3" GM Maf w/ MAFT
Larger cams (unknown brand or grind) think I have some pictures if someone thinks that's relevant
Apologies for the essay. Any insight into the problem would be appreciated. I haven't got a vacuum/boost leak tester available to me - so any ideas of diagnosing without one of those would be golden as well.
Thanks!
