89 M20 running on 3 cylinders, 2,3,6??

[noE30]

Working to get my e30 out of storage this spring as it hasn't been driven regularly since 2015, and seems to be giving me issues left and right.
Here's some background on what has been replaced since its been parked, my car is located in Iowa and I live in Colorado now so I've been going home periodically to replace parts with the hope to get driving reliably again.

New Battery - (Summer 2020, when I first tried getting it running again, charges fine as of last week.)
New Fuel pump/filter - (Summer 2020)
New Fuel Pressure Regulator - (March 2023)
Re-manufactured M20 Injectors from Catuned - (March 2023)
New Bosch Spark Plugs - (March)
New Dist Cap and Rotor - (March)
Coil and Spark wires are only a few years old
New Crank Position Sensor - (Old one had frayed wiring and didn't seem to be working, replaced Summer 2022)
Timing Belt , WP, Tension-er - (Summer 2022)
*Rewired/Replaced C191 Plug - (March) Replaced with a "Weatherpak" style connector as 3 of the old pins were corroded heavily.
New Fuel and Main Relays - (Oct 2022)

Here's were things get confusing for me, the story is as follows:
I replaced the CPS as my car wouldn't start at all ( hard cranks but no turning over), and I could tell it had some fraying, this was done while I put a fresh Timing Belt Kit in. Reinstalled everything and still couldn't turn the car over. Found out that the replacement CPS was out of spec range and was reading way too high of resistance. Relays gave us some strange readings with the multi meter as well but I couldn't source any locally and was flying out the next day, so I decided to order another bundle of parts and plan another trip back home in the fall.

Returned in the fall to replace relays, another new CPS, and get fresh gas, as we felt that the car wasn't getting fuel due to the bad relays/CPS not communicating to the ecu and/ or bad gas in the tank. At this time we found that the engine was testing well for power at the coil/ plugs. Still nothing, though the car would run very briefly if we sprayed starter fluid into the intake, so I assumed it was still not getting fuel INTO the engine. Fuel pump and relays all checked out good at this time, though the C191 was found to be corroded heavily on 3 of the male pins. Time to plan another trip home and try again.

I just returned from Iowa last week having spent the entire weekend wrenching on the car. New FPR installed thinking that the bad gas may have clogged the older one along with re-manufactured injectors from Catuned as the ones installed were the original ones as far as I knew. Rewired the C191 with a weatherpak style connector, now I fully admit to not having much in the way of wiring skills though I did read/ watch every video and thread about the C191 over the last few months. At this point I installed the new spark plugs as we were able to get the car to start and idle, I was afraid to install them earlier as I didn't want to foul the brand new plugs while trying to crank the engine over again and again.

The engine now cranks over and starts faster than it ever has before (no more hard start cranking) but seems to be only running on 3 cylinders. I'm tentatively thinking that I could of done something wrong here with the C191 BUT whats confusing is the engine is running on cylinders 2, 3, & 6.. We pulled the spark plug wires at idle and found that cylinders 1, 4, 5 didn't cause any change in engine performance. At this point I installed the new Dist Cap and Rotor that I had been holding on to since the previous visit, the unit I removed did show signs of arcing on a few of the contact points so we hoped the fresh unit would solve our problems, though it did not..

Am I correct in understanding that the C191 as one wire for the even number cylinder injectors and one for the odds? That seems to conflict with the idea that engine is running on 2,3,6 cylinders right? Some even cylinders and one odd? Is it possible that I screwed up one of the wires for the coolant temp sensor, resulting in a bad reading from that sensor and telling the ECU to go into some strange 3 cylinder " Limp Mode" ? Also seems very strange that the engine no longer has the hard start issues that plagued it years passed though now it wont run on all 6 cylinders. I should note that the O2 sensor code did get thrown once during the weekend, though it went away after disconnecting the battery and it never came back, I know a bad O2 can effect the way the engine runs, I just want to try troubleshoot a bit before I order a new one. All fuses check out as well, is there something else that's obvious I may be missing?

Now that I'm back home, I'm planning to have family haul my e30 out here to Colorado in the coming weeks. So at this point I'm hoping to do some mental troubleshooting prior to getting my hands on the car again.

TLDR: Cars been siting since 2015, lots of new parts installed listed above, starts quickly and idles but runs on 3 cyclinders #2,3,6. Where should I look next?

[digger]

If you confirmed spark on all 6 and removing 3 doesn’t affect the running then I’d look to see whether injectors on those cylinders are firing. If not then bad connector or wiring associated those particular injectors.

[noE30]

If you confirmed spark on all 6 and removing 3 doesn’t affect the running then I’d look to see whether injectors on those cylinders are firing. If not then bad connector or wiring associated those particular injectors.

Thanks!

I think what I’m hung up on is my understanding that the fuel injector wiring /C191 connection has a wire for the even # injectors and one for the odd # injectors. Seems strange that I’m experiencing issues with some of each set.

The injector connectors did test to get 12v when the key was turned on.

I suppose I should of pulled the spark plugs on the problem cylinders 1, 4, & 5 to check for unburnt fuel. What’s the best way to check whether the injectors are firing?

I guess it’s possible that I received 3 faulty re-manufactured injectors but that seems unlikely.

[DesertBMW]

if the car sat since 2015 and you never flushed all of the old fuel out then even small amount of old fuel mixed with new fuel will cause the injectors to stick closed. And valves could stick open, with valves stuck open, the starter will spin the engine faster

[noE30]

if the car sat since 2015 and you never flushed all of the old fuel out then even small amount of old fuel mixed with new fuel will cause the injectors to stick closed. And valves could stick open, with valves stuck open, the starter will spin the engine faster

Interesting, I did siphoned most of the old fuel from the tank last fall before adding 5 gallons of fresh fuel. Obviously I can't confirm that I removed all of the old fuel, though I did purge a bit from the lines leading up to the engine bay, as I replaced the hoses within the bay leading from the fire wall to the FPR/Fuel Rail.

[66Vette]

First, full disclosure. I am new to the M20 engine. I have mostly dealt with (built and raced) carbureted domestic stuff. I'm an electrical engineer, but have never been deep into a computer controlled engine. My latest project is a 2002 with a swapped M20, so I have been reading up on and studying the M20. (I even have a second M20 on a stand in my shop for reference.)

That said, you never confirmed you checked for spark on all six cylinders. A quick and dirty way to do this is to take your timing light and clip it to each spark plug lead. Spark will be indicated if the light on the timing light flashes. A more complete test is to pull each wire and use a ignition-spark tool to observe a healthy spark at each cylinder. I have been fooled by the timing light test when I had a weak ignition system. It would fire the timing light, but was inadequate to jump the gap in the spark plug.

https://www.autozone.com/test-scan-and-specialty-tools/ignition-tester/p/oemtools-adjustable-ignition-spark-tester/10257_0_0

To test to see if you have injector pulses, there is a tool called a noid. It is simply a light that you plug into the injector connector. It will flash with the injector pulses. Here's an example:

https://www.ecstuning.com/b-schwaben-parts/noid-light-tester-set-of-2/lcb141sch/

If both these tests pass, I would recommend you switch injectors from a known bad cylinder to a good cylinder. This would help identify a clogged injector.

Keep us posted

[noE30]

First, full disclosure. I am new to the M20 engine. I have mostly dealt with (built and raced) carbureted domestic stuff. I'm an electrical engineer, but have never been deep into a computer controlled engine. My latest project is a 2002 with a swapped M20, so I have been reading up on and studying the M20. (I even have a second M20 on a stand in my shop for reference.)

That said, you never confirmed you checked for spark on all six cylinders. A quick and dirty way to do this is to take your timing light and clip it to each spark plug lead. Spark will be indicated if the light on the timing light flashes. A more complete test is to pull each wire and use a ignition-spark tool to observe a healthy spark at each cylinder. I have been fooled by the timing light test when I had a weak ignition system. It would fire the timing light, but was inadequate to jump the gap in the spark plug.

https://www.autozone.com/test-scan-and-specialty-tools/ignition-tester/p/oemtools-adjustable-ignition-spark-tester/10257_0_0

To test to see if you have injector pulses, there is a tool called a noid. It is simply a light that you plug into the injector connector. It will flash with the injector pulses. Here's an example:

https://www.ecstuning.com/b-schwaben-parts/noid-light-tester-set-of-2/lcb141sch/

If both these tests pass, I would recommend you switch injectors from a known bad cylinder to a good cylinder. This would help identify a clogged injector.

Keep us posted

We had tested for spark by taking a known working spark plug and placing it in each individual plug wire and holding it near and engine bay ground. I suppose that confirms that the distributor/coils/ wires work but not the spark plugs themselves specifically. I’ll look into a test light like you linked above.

[66Vette]

Through all that swapping, could the spark plug wires be in the wrong positions on the cap for cylinders 1, 4, and 5?

Not sure why, but through my digging on the M20 engine, I find very few times where a timing light is used to troubleshoot the motors. I have marked up my crank trigger wheel for TDC (cylinders 1 and 6 fire), then 120 degrees later (cylinders 5 and 2 fire), and finally 120 degrees later (cylinders 3 and 4 fire). The nice thing about the trigger wheel is it is (sorta) degreed. Each tooth is 6 degrees of crank rotation. So count 20 teeth for 120 degrees. You can examine timing on each of the cylinders this way. You can't adjust anything as the DME controls timing, but its a good sanity check.

[TobyB]

And valves could stick open, with valves stuck open, the starter will spin the engine faster

Bad gas will not make valves 'stick open'. Likewise, it won't magically convert 'good gas' to its evil ways.
What CAN happen is that the sediment that it leaves behind, (because sticking corn alcohol in your petroleum fuel is
a truly boneheaded idea, ) doesn't get flushed out, and it then clogs things anew. Which sucks.

t