D-Jet Injector Points
 

Can the injector points on a 2.0 D-Jet be in a state of continuity all the time due to touching something in the dizzy?

I'm checking the ECU harness for some sporatic injector behavior, and when I check continuity between terminals 12 & 21 (trigger contact #1) there is none until I crank the engine and I get alternating continuity.

But when I check terminals 12 & 22 (trigger contact #2), I get full continuity as soon as its connected. It still alternates when cranked, but the continuity returns when I stop cranking. This would indicate to me that contact #2 must be touching something inside the dizzy.

Any ideas?

Many thanks,

Gerard, I'm having problems with an erratic miss and probably will be checking continuity from the ECU to the various harness ends. In order to do this do you need to pull the ECU and expose the area where the leads begin? I've never done this so I'm having trouble explaining what I need to know!
bruce

Bruce,

No need to pull out the ECU. Just undo the screw at the base of the ECU that retains the cable. From there slide down the charcoal color cover. It should slide completely off. Once the covers off, grab the exposed plastic portion of the connector (this is just a cover) and slide the connector out.

From there the connector is exposed. I use small alligator clips to test with. The wires are numbered 1 - 26 from the top to the base (where all the wires collect).

Good luck,

PS: If you haven't seen it, here is Brad's page on the ECU terminal layout: http://members.rennlist.com/pbanders/ecu.htm

Hey Gerard,

12 is the common for the dizzy points and 21/22 are the 2 poles. As long as you get alternating action as the dizzy rotates you are fine, as that is what triggers the two banks of injectors in pairs.

Brad Anders web page has the full info for diagnosing each component thru the ECU connector on the FI harness. Note that there are only 25 slots, but that 3 are not used, making a total of only 22 wire terminals available at the ECU connection.

3d914 - when the tab that runs against the shaft of the distributor gets worndown, it will get where there's not enough left to break the points. short term fix is pull the point plat and bend the tab away so the point will break. A better way is buy new points, or replace with a better set.

Re: D-Jet Injector Points
 

The trigger contact points alternate continuity between terminal 12 (common) and 22 and 21. If you're seeing alternating continuity during cranking, that's normal behavior. Resistance (as measured at the points, not at the ECU plug) for new points is about 0.1 ohms.

your dizzy might just be stopping at a position when the 2nd set of points are closed. check continutity to ground if you are looking for a short.

I have found over the years that even if you measure the points and they seem to look good when turning the distributor and the erratic running will not clear up, a new set of injector points will fix things? I have no clue as to why but I have done this several times since we have owned our 74 2.0l and each time I could have saved a bunch of time if I had put in new points! Good luck.

Thanks guys,

I have yet to check the continuity to ground, but I've aquired a more serious problem. In a short test drive, the engine developed a very prominant clank, clank, clank. The sound appears to be coming from #3 cyl. SOo I limped it home. I started it Sunday morning to put it on the ramps and pull the valve covers and the noise was not so prominant, but still there. I didn't check valve clearance as this is a newly rebuilt engine, but I was looking for obvious things like misaligned rocker arms, push rods out of cup, etc. Everything looked OK.

Soo as they say - back to the drawing board.

Just went thru all the elec. components from the ECU. T'was quite enlightening!:) I found that all connections were quite good AND the PO had the injectors connected backwards. The only connection I didnt check was the one from the ECU to the 12V. That one didn't make sence to me as to where or how to check the continuity but, at least, I found part of my problem. Most of the erratic miss is gone and it still takes 3 tries to start before it will keep running. I'll check the cold start injector along with changing the fuel filter.
bruce

Gerard, check the valve adjustment. A freshly-rebuilt engine will change valve clearances as it "wears in". (The bits that get scraped off of everything as it all wears in is the main reason you change the oil very very frequently during break-in.)

A "clank", particularly if it is in time with engine RPMs, is likely a valve with too much clearance. BTW, 1/4" of clearance sounds more like "THWACK!" Don't ask how I know this...

--DD

Dave, I won't be the one to ask how you know that, but I've been reading a lot of old posts lately to learn about chaning the pushrod tube seals. More than once you've mentioned what a pita it is to get the pushrod seated in the rocker arm when reinstalling the assembly. ;) Thanks for sharing your experience!

--Case...

Yeah, I was hoping that was my problem. It wasn't.

(Hint: The valve seat is about 1/4" thick...)

--DD

:eek: