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Rich Fuel Mix on B230 Engine[200/1985] posted by Ed Wright on
Saturday, 7 November 1998, at 9:54 a.m.
I have a 85 245GL with the B230 Engine. It failed the VA emissions inspection due to burning too rich. Had lots of things replaced (Air Mass Meter, all tune-up parts, found a leaky vacuum hose, new catalytic converter (before I realized its electric)).
Found a short in the wiring harness on the firewall (at a grey junction box). Fixed this, but engine is still burning rich (rough start when cold, then a little vavle knocking when hot).
Can anyone tell me if the Air Mass Meter got shorted by these bad wires, or should I look at the ECU???
I got the waiver for the emissions inspection (by spending too much money on repairs), and I don't want to go broke getting this thing to run well again.
Re: Rich Fuel Mix on B230 Engine[200/1985] posted by Mike on
Saturday, 7 November 1998, at 10:41 a.m.
Ed,
One thing comes to mind, when you replaced the AMM, did you set the mixture? I had a similar experience with an 88 245, where the owner (a friend from work) simply plugged the new AMM in, but car failer emissions. Simply setting the mixture, using a digital volt meter and the O2 sensor let the car fly through emissions here in Ohio.
I would not expect a wiring short at the junction box to affect the AMM, and I assume by an "electric catalytic converter" you might be referring to the O2 sensor. You will need a good O2 sensor to set the mixture using a digital volt meter. Not sure if your set-up has the cold start, if so you might make sure its not leaking. Good luck.
--Mike Gambone
Re: Rich Fuel Mix on B230 Engine[200/1985] posted by Don Foster on
Saturday, 7 November 1998, at 12:17 p.m.
Ed --
Three thoughts:
- The fuel pressure regulator may have gone south (or be heading that way). The fpr is a cylinder about 2" long and 2" diameter mounted a few inches behind and aside of the distributor cap. It has a hard-piped fitting on the top side, connected to the fuel rail, a small diameter vacuum line connected on the front, and a flexible fuel (return) line connected on the back.
- The small vacuum line may have a crack, or might have broken off where it connects to the intake manifold. The higher the vacuum delivered to the fpr, the lower the fuel pressure, and the leaner the engines runs. If the vacuum line breaks, the fpr delivers too high pressure -- and the engine runs rich.
- The FI ecu receives a signal from the temperature sensor mounted in the head (I think it's under intake manifold, at approximately runner #3). If the wires or connections become corroded or broken, it tells the ecu the engine is cold, and forces the mixture to run rich. A broken wire there tells the ecu it's about -50 degrees, so the engine gets tons of fuel!
And one final thought -- if your engine has been running rich for long, the oil might be diluted. It wouldn't hurt to change the oil & filter at your earliest opportunity. --
Saturday, 7 November 1998, at 12:19 p.m.
Check the ground wires on the injectors. Solder the wires to the crimps. This connection gets hot and acts as a high resistance and ane or more infector does not fire. This pumps air thru the cylinder without burning and the O2 sensor give me more fuel which it cannot burn.
Don Willson, '86 744, 115,000 miles, '89 765T, 135,000.