Question about 740 GL timing

Its an 89 740 GL sedan, non-turbo, B230 F engine. Jetronic L system. I am not sure I have it timed right. It idles rough (erratic RPM....500-800 RPM), it has a strong miss every few seconds (when the RPM dips).....but only when you have it in park! When put into drive--- sitting still--- the idle RPM is perfectly stable, roughness/missing is completely gone. And when moving, the miss is still gone. Went and spent a lot of $$ for new dist. cap & rotor, new plugs, new spark plug wires. Now I notice that it is only running badly when in PARK, so it wouldn't have been any of those parts! If not timed right, can this cause the ign. control module to maybe set the advance way off for PARK, but set it correctly when in DRIVE?

Reply to
Geronimo
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Does it run poorly in Neutral like in Park?

Ger>

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

Yea, runs poorly in neutral, also...same thing.

Reply to
Geronimo

Geronimo,

The ignition timing on that motor (if it's adjustable at all) needs to be set, with the engine FULLY warmed up, as an ECU monitors the coolant temperature, and gradually retards the ignition from an advanced condition that exists with the coolant anything but fully warmed, this allows the engine to run 'nicer' when cold. The same ECU also monitors the status of the neutral start switch, very slightly advancing the ignition timing if a gear is selected, helping to prevent stalling while the engine is idling in gear. I'm not sure if the ignition timing on the B230F is picked up from the camshaft via a hall sensor in the distributor or the crank shaft via a position sensor 'reading' the flywheel, if it's the later, AFAIK, you can't actually change the timing, but, if you rotate the distributor too far either way, then it's quite possible to have the ignition firing sparks off, when the rotor arm is actually not close enough to a spark lead, to actually get to a plug properly, hence causing a slight or not so slight misfire.

Just my 2 pennies worth,

Ken Phillips

Reply to
Ken Phillips

I determined crankshaft position by a crank position sensor mounted on top of bell housing (reading the flywheel). I don't think the distributor can be turned on this engine. All the Haynes manual says to do is line up the mark behind the crankshaft pulley and line up the mark on the camshaft pulley. It shows you how to position the idler pulley...but it is only an idler, and it says it is not critical. The camshaft mark is definitely lined up with the index mark (at 11 o'clock) and I verified that I had the crankshaft at TDC (firing) by pulling the #1 spark plug and finding the highest level. But I think my procedure is not right, and it is not timed right. Seems real sluggish accelerating to 60 MPH, allthough as I said the roughness/missing is gone when in any DRIVE gear, even if stopped.

If it smooths out in DRIVE because the computer advances the spark, then would this indicate I have the timing too retarded?

Thanks!

Reply to
Geronimo

If you don't have all the slack in the belt on the tensioner side of the motor before you relase the tensioner, the belt pulls the crank wheel clockwise. When you turn the motor over two times by hand to check the tension, you will see that the cam has retarded one tooth. The trick is to start the belt arounf the cam pulley and clip it with a clothspin clamp and pull the belt snug around the crank pulley, then release the tensioner.

Bob

Reply to
User

"Geronimo" skrev i en meddelelse news: snipped-for-privacy@4ax.com...

Since this engine has a crankshaft position sensor in the bellhousing, the timing belt has nothing to do with ignition timing, which can not be adjusted. The timing belt is only for the camshaft timing ( and the oil pump which wont need timing ). If the timing belt has been set incorrectly the engine will run poorly, but again it's not an ignition problem.

I'm not sure what it means, the 11 o'clock position you refer to, but you should have a look on theis website, and maybe it can be of some help to you.

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Regards

Per Hauge

Reply to
Per Hauge-Nielsen

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