Tech Forum : Cold idle problems HIGH HC's

wharthog	Posted Monday, Feb 19th 10:35am [Edit] [Quote] [IMS] [View car]
Member Post nr. 120 SF Bay,California, USA 1982 323i, , R1150RT	When I bought my '82 323i it would stall when cold. I did the sensible thing and replaced the aux. air valve. Problem solved... until about 4 months later. it's back. as well as a low idle. Took it to my buddy's shop to put it on the sniffer and tune it and found the HC level in the 4000 range. Warm up regulator appears to work. hot compression is 210-215 on all six cyls? I tuned everything i could but HC's are still at 2300! The car runs well hot but still doesn't want to idle cold and doesn't like to start again when I lose it. Any ideas? This is driving me nuts!

Madhatter	Posted Monday, Feb 19th 11:09am [Edit] [Quote] [IMS] [View car]
Member Post nr. 115 Australia - QLD E21, E24, E30	High HC's is due to incorrect combustion, coupled with your poor idle i would say you probably have a misfire somewhere there too. A few things cause high HC readings, they are all related to the combustion process; Bad/fouled plugs Bad leads Misfire under lean conditions Burnt exhaust valves Rich fuel state Higher CO (carbon monoxide) emissions will accompany high HC readings if its running in a rich state, where a lean misfire will only usually see HC readings spike (while CO remains fairly normal). If the above is true, mixture is incorrect and you need to look at causes like a faulty temp sensor/temp time switch, leaking cold start injector, stuck/faulty thermostat or warmup regulator issues before tuning the engine. If you exhaust the above and have the engine tuned, make sure you take it to someone that knows jetronic stuff. They absolutely must have a good fuel pressure test kit (needs the appropriate higher pressure gauges and mechanical injection fittings)and a set of vacuum gauges along with the usual emissions tester. If however the CO remains fairly normal, the problem is more of a lean issue which points to problems with spark, so plugs, cap, leads, coil, etc, plus dont forget things like vacuum leaks or low fuel pressure are the usual culprits. Anything more extreme like valve issues should be detected with a compression/leak down test, so you are probably pretty safe there.

imaradiostar	Posted Tuesday, Feb 20th 12:14am [Edit] [Quote] [IMS] [View car]
Member Post nr. 1018 Nashville, TN 81 323i, 82 525i, 85 524td, 90 535i	does the shop in question have fuel pressure tester for CIS systems? It would be helpful to know if the control pressures are in spec both hot and cold. jamie

pjs323i	Posted Tuesday, Feb 20th 1:41am [Edit] [Quote] [IMS] [View car]
Member Post nr. 51 Canberra, Australia '81 323i	my car has the same issue, so i looked in the phonebook...and i found a bosch injection specialist! but sorry its in australia. My point is: its good to see someone else with the same issue as me! this has been driving me nuts since i got the car in august '06 I'll get mine checked out and I'll give you the diagnosis.

wharthog	Posted Tuesday, Feb 20th 6:21pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 121 SF Bay,California, USA 1982 323i, , R1150RT	Thanks PJ let me know what happens. As for the CO 3.3%, CO2 11.3, no leak on the 7th injector. The control pressure on warm up climbed normally from 1.5 to 3.6 bar. The WUR appears to be working normally. I checked 4 of the six injectors for spray pattern, they seem to be ok. I replaced the plug wires... I was thinking of trying new cap/rotor and new injectors, but I hate to just keep throwing money and new parts at the problem... The fuel pressure was1.7 off idle and at low lumpy idle it was 1 bar. I smoke tested the intake manifold and there were leaks at the throttle shaft but all else was good... My friend noted that the centrifugal advance return springs feel weak... I know it's hard to diagnose on line but this is driving me and my buddy crazy! Any thoght that maybe i just got a bad aux. air valve, because that seemed to solve the problem the first time. oh ya. also if the car is luke warm, like I drive to the store park for a few and start again, it has a really fast idle, like almost 2000 RPM

imaradiostar	Posted Wednesday, Feb 21st 2:02am [Edit] [Quote] [IMS] [View car]
Member Post nr. 1020 Nashville, TN 81 323i, 82 525i, 85 524td, 90 535i	how is your control pressure 3.6 bar and the fuel pressure only 1? Seems that needs to be double checked. jamie