74 2.0 D-Jet. Car is in a fine state of tune. Verified fuel pressure at 30 PSI. Removed distributor, cleaned & lubed advance plates and tested vacuum canister. Verified TPS is set correctly. MPS tested fine. ORIGINAL fuel injection harness. I went around the engine bay today and re-seated all FI related connections. The injectors are in unknown condition - came with the car.

This is different than the bucking I used to experience. I intermittently have a cylinder drop off. It happens at all speeds, but is really noticeable at idle. I had it running for a while in my driveway tonight and the exhaust fumes spelled especially "gassy."

When it's not missing, it runs fantastic and idles perfectly.

I think I have a fuel injector going bad. Can they fail intermittently? Anyone else experience something like this?

I figured I would just pull all four injectors, run the fuel pump and measure the fuel...but I'm not sure I could find the faulty one if it functions correctly during the test.

Pretty boring video Engine starts running rough intermittently at :40 (engine bay sound) and 2:07 exhaust.

https://www.youtube.com/watch?v=xQoMS-NeOag...eature=youtu.be

Any advice is appreciated.

I would suggest disconnecting the injectors one at a time to see which cylinder is falling off. Given the intermittent nature this will determine if it is injector related or something else.

If you pull the misfiring injector while it is missing then the engine won't change. Just a thought and easier than removing all of the injectors.

Just a thought.

If the injectors have never been cleaned, consider sending them to mr injector. $16 each and they come back looking like new and flow tested. Fast turn around too.

The quick and dirty is to remove the wire one injector at a time, then remove the offending injector and push on the pintle with a pin. You should feel a click movement.

If the pintle moves the injector is likely OK and it's a conection issue.
If the pintle doesn't move the injector is seized, cleaning is a 50/50 crapshoot in this case, if it doesn't loosen up you have to replace it.

Connections /connectors at the injectors was a problem I encountered. Didn't find the defects until I removed the harness and did a continuity test on all the wires.

i had a similar issue with my75 d-jet and thought it was an injector, sent them in for testing and cleaning and they were spot on and flow was within1% of each other, not bad for 40 year old car - but here are 4 things to check ive had each of these at some point in the 6 years of owning the car
1. the F.I. grounds , they can come loose and will feel like you are firing on 2 not 4.
2. F.I. trigger points plate - usually dont fail but you can pull them and clean them
3. Recently this happened for no apparent reason- Bad cap/rotor - acted just like a bad injector or plug or wire, it was intermittant and would happen if i did not drive the car for a few days which made the mechanic think it might be a bad injector sticking open, if i got the car started(sometimes it would not ) it would clear out and be fine for a few days - but also seemed to be effected by temperature or humidity- it was so simple but one of the hardest things to chase - ended up being the spring in the center connector of the distributor that goes to the coil, so it would not always make good contact.
4. old wiring harness shorts etc- I replaced mine with a new one from Jeff Bowlsby . Now i know i have good connections and no shorts due to cracks in the old insulation.

Good luck!!!

I have had the following.

Loose electrical connector at injector...wiggle loose randomly, fixed with new boots
Old worn out FI trigger points, new trigger points
Fuel filter clogged, crap in tank.....full douche, two new inline filter.

All of those problems gave me your conditions...all are pretty cheap to fix...

Rich

duplicate

Who is "Mr. Injector" and how do I get in contact ?

http://www.mrinjector.us

Sorry, I see he raised his price by $1.
I highly recommend him.

Group,
I've used the original bosch dizzy and replaced the centrifugal advance plate with a missing tooth trigger wheel and a hall effect sensor on the FI points plate. I then install a sequential port driver PCB on a Megasquirt II ecu and build a duplicate D-jet harness. It is all mounted in the D-jet ECU box and looks just like a stock D-jet. Full sequential port fuel and fully programmable engine management.
I've built 6 of these systems for D-jet Volvo's and all have been running for over a year. Last year I put 13K on my 1800 without a fault or issue.
See stealthems.com Stealth Engine Management Systems

Thanks for the responses. The trigger points were inspected and cleaned earlier this year when I pulled the dizzy to clean and lube. The fuel filter was the first thing I suspected, so I replaced it a few weeks ago. FI grounds look good. Climbed under the car yesterday to verify there were no fuel line kinks under the tank.

As suggested, I started the car and pulled the FI connections one cylinder at a time. Found the problem to be with the #3 injector.

I'm pulling all four injectors and shipping them out to Mr. Injector for cleaning and flow test. I know the car has been run with sediment in the tank. If this doesn't fix it, I'll move on to the harness.

Thanks for the info on Mr. Injector Mark. Seems like a great value.

Use a $6 usps priority box and you might have it back by this weekend. He's fast.

I've used Mr. Injector several times for a couple dozen injectors and have always been pleased.

I believe I have eliminated everything but the ECU and the FI harness at this point - please let me know if I've missed anything as my next step is a Blowsby FI wiring harness:

Injectors cleaned & tested by Mr. Injector. The worst one was only 10% flow deficient, so I had my doubts that the injectors were the problem. Installed the fresh injectors and still have the same problem.

Inspected inside fuel tank for debris and condition of fuel sock - all looked very clean.

Swapped out relay board - no difference.

Swapped out cap, rotor, points & coil individually - no change.

Inspected all fuel lines (including under the tank) for kinks.

Fuel pressure spot on at 30PSI

Props to Mr. Injector. Total turn around time, including shipping was 9 days. Injectors came back cleaned & inspected with new FI seals, FI hose clamps, lengths of hose and documentation on how the injectors tested. A true value at $17 per injector.

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Hey Bob - sorry to hear you're still chasing this. It is a good feeling knowing your injectors have been serviced and not the issue, though, and Mr. Injector does do a great job.

I was having similar issues, and I wish I could say I found a "smoking gun." I did replace the wiring harness with a "Bowlsby-special," and my problems are in fact gone. It's hard to tell if that was 100% the cause, because I initially struggled to get the grounds wires connected securely, and I also had an issue with a loose fuel pump connection at the relay board on the new harness (cut out on me near my house). I also replaced the spark plug wires and tried to make sure they routed clear of other wires (especially #3 which apparently sometimes causes electrical interference). Everything is running like a champ now, though, particularly after doing some MPS fine-tuning. If you can, I'd definitely consider investing in the new FI harness, as it can help eliminate a lot of potential variables as you disconnect/reconnect sensors and other odds and ends.

Do you have an O2 sensor? Did you inspect/replace the TPS or just calibrate it? Is the MPS actually steadily holding a vacuum? That's all I got...sorry.

I'll ship you the ecu and harness from my '73 if you think it will help troubleshoot.

When you tested your fuel pressure and you said it was spot on, does that mean the needle in the gauge stayed pretty steady? When I checked mine last week, it was high, so we set it at 31 as other 2056 guys said that was where they set theirs, but the needle jumped around a bit, kinda bouncing between 33 and 29, not steady at all, so if that's not the normal behaviour what do you think is happening with mine, trigger points maybe??

Ian Stott
Moncton
Canada

I just checked my fuel pressure today and adjusted it back toward 29 psi. That's kind of my experience - it bounces around a fair amount (anywhere from 1 to 3 psi of variance). Not sure if it's a cheap gauge, but I just kind of try to find the 'average' of the bouncing around.

I think the bouncing is normal. I got it real close to 30 with the car running. Immediately after shutting it off, I checked pressure and it showed 30PSI with no bouncing.

Appreciate the offer Mark. I'm going to order a new Blowsby harness and see where it gets me first. I'm pretty sure it's a problem in the harness at this point.

Another possible problem would be the trigger points in the distributor. You'll drop two cylinders when these act up. Also if your smelling gas, your ecu drivers may be holding the injectors open making it miss by being way too rich. The ecu on ours went bad and would intermittently miss due to fouled spark plugs. If you can duplicate the condition, shut the motor off and check to see if any of your plugs are fuel soaked.

Well, the problem is fixed!

I filled up the tank last night and checked my gas mileage - 22 MPG. I normally get about 28. The car was running rich at all times...idle would drop to about 250 RPM.

Before popping on a new Blowsby FI harness, I wanted to rule everything else out first. Jim gave me a loaner ECU so I swapped it out today - no difference.

I went back to the good old d-jet bible in the troubleshooting section under "my car runs rich and I don't know why" for a comprehensive list of things to check.

http://members.rennlist.com/pbanders/DJetParts.htm

Ran through the list one by one - nothing helped. Then I got to the trigger points. Several world members indicated that they may be the problem. I had previously assumed these were not the problem because I cleaned and inspected them over the winter when I cleaned & lubed the disty.

Well, some grease from the lube job had collected on the trigger points. I swapped them out with another clean set, started the car and reset the timing/dwell. She is running as good as ever again! I think my old trigger points will be fine with a good cleaning - I'll test the theory next time I have the dizzy out.

I've spent a few very frustrating weeks on this...lesson learned - don't rule anything out because you "just serviced it."

Thanks for all of the advice on this topic - much appreciated.

Awesome! Congratulations!
Glad it was that simple, many times it's the simple one that's hard to find, or we dismiss it and don't go back and recheck it ! I spent 3 months trying to figure out a similar issue and ended up just putting in new cap and rotor, that was the issue!
Now drive it lime you stole it!

Great News Bob! Glad it worked out for you and I bet you understand D-Jet a whole lot better by now.


Jeff BOWLSBY