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Cold start/driveability problem 89 300e

2K views 3 replies 2 participants last post by  p7fan 
#1 ·
Hi all! Working on a friend's 89 300e. Has 288,00 miles and a very poor (minimal at best) maintenance history. Takes multiple attempts to start cold, when it finally fires it has a low unstable idle and hesitates badly during warm up. Hot restart is fine, did idle somewhat roughly when hot.

Swapped known good OVP from my 89 300TE.
Smoke tested and repaired a couple of small vacuum leaks, replaced all injector and holder seals (leaking badly).
Replaced #6 wire (burnt from manifold)
Gave her 1/8 turn in (rich) on AFR adjustment---now idles great when hot.
Upper chamber pressures right at 5.5 bar, lower exactly .4 lower.
Inspected cap and rotor (not new but close to it)
Replaced partially restricted fuel filter.
Ohm'd coolant temp sensor, airflow sensor, throttle switch-- all ok
Cleaned ground connections at intake.
Checked cold start injector pulse.
Swapped known good FPR from my 300TE
Swapped EZL from my 300TE
Checked air flow "plate" position and for smooth movement
It does hold fuel pressure (2.5 bar IIRC) overnight
Ohm'd crankshaft sensor

A couple of observations; When cranking cold, has good spark, and fuel pressure. Will typically fire when RELEASING the key from the start position (ignition switch failing?) Sometimes the overhead dome lamp flickers (almost like an ignition pulse) when cranking cold. The EHA does have some fuel(?) moisture/residue at its harness connector. Although unplugging the EHA makes no difference on cold start (shouldn't that throw the KE into a strictly mechanical setup?)

Sorry for the length of this post but I wanted to include all the info/diagnostics. Any help would be GREATLY appreciated. This one has me stumped!

Thanks

John

PS--debating whether to pin out the ecu next....but it wont fire off cold on "backup"....and I'm going to put a new EHA on tomorrow anyway because of the leak...
 
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#2 ·
Additional info.... I also checked the inlet screen on the fuel distributor (ok). When I keyed it up I got a good shot of fuel in a container (i' assuming volume is ok, fuel quality looks good as well). Car has been doing this for some time but has gotten worse.....
 
#3 ·
Wow, if I didn't know better, I'd think you were describing My car. I was having the same symptoms have done everything you have listed and finally got the car drivable... not 100% fixed but drivable. I'm beginning to think my main problem was bad gas, exacerbated by needed maintenance. (My daughter was driving the car when the problem developed so I don't know where she was buying gas but it was probably a low price, no-name independent retailer). After I did the tune-up, I could drive it, but it had a low idle and O2 Sensor Light lit. I drove it around for a week like that. After filling the gas tank with premium and driving for about 10 minutes, the O2 Sensor Light flickered, the idle started jumping. Eventually, the light turned off and idle smoothed out to about 700rpm. It has started and run flawlessly for the past three days, until today. Still starting great, but when the car reaches full operating temp the O2 light is flickering on accompanied with dropping idle when the light is on, normal idle when the light is off. the gas tank was about 1/4 full when I filled up, so I may still be getting some effect from the residual bad gas, or possibly an intermittent bad ground. I think I'll drain my gas tank, and clean and recheck my ground points. I'll keep you posted with the results.
 
#4 · (Edited)
Car is fixed!!

Now let me tell the world about my "brain fart". Buddy stated that he had the car tuned up a while back...didn't help it any but didn't hurt it either. So i didn't bother pulling a plug. Damn I'm po'd at myself!! I know better!!

Pulled a plug and found a set of Autolites gapped at .065!!

Put in a set of properly gapped Bosch and she runs like a new one...

John

i guess the poor thing didn't stand a chance with the restricted fuel filter, horribly leaking injector seals, and the dorked plugs.....
 
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