1985 dodge omni glht cylinder 2 acting up, breaking up under boost

So cylinder two seems to be acting up compared to the others. I was having a misfire and it was breaking up under boost so I started pulling plug wires to see which one was giving the issue. Pulling all the other wires made the car idle poorly but pulling the cylinder two wire from the distributor cap gave no change. I then checked for spark and it has spark there was still no change so I swapped wires and that didn’t change anything either. (Btw changed out HEP plugs wires OEM ignition coil cap and rotor) so then I went to the injector harness and checked cylinder twos injector harness connection and the ground contact inside seemed to be missing so I exchanged it with a known good injector harness with no change. Cats idling at about 14-15Hg. Cam, crank, ignition timing has all been set previously which leads me to believe theirs a failing component. Did a vacuum leak down test and I had no leaks detected. This is why I suspect cylinder two is causing all these issues.

So you have fuel (at least the injector is firing) , air, spark and compression. Time to check the valve train. If that looks ok, maybe try swapping injectors.

Compression test?

Thanks. Idk how that slipped passed me. I have 803s with less than 100 miles I really hope one isnt messed up. I will swap around injectors and see. ( valvetrain checks out)

with many of these cars being 30+ years old, i suggest taking a fine tooth comb to the wiring and ECU's.

deoxit is your best friend. red and gold cleaner and connection protector. i have a 31-36 year old harness that works great due to this stuff.... one on my car and one on my bike....

a simon style headlight test is your 2nd best friend (a headlight pulls significant current.... use that to test connections to see if they are decent connections that a metered ohm test may not pick up unless loaded heavily as with a headlight) ..... yes i know.... in the past i argued with simon that a headlight was too much for some of the small wires in the harness. i did some calculations later and realized that the current wasnt all that excessive, especially for a short term test.

Brian

How does the headlight load test work? I read what you wrote and I sorta get it, sorta;)

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Originally Posted by tryingbe

Compression test?

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x2, did you do this?

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Originally Posted by Aries_Turbo

with many of these cars being 30+ years old, i suggest taking a fine tooth comb to the wiring and ECU's.

deoxit is your best friend. red and gold cleaner and connection protector. i have a 31-36 year old harness that works great due to this stuff.... one on my car and one on my bike....

a simon style headlight test is your 2nd best friend (a headlight pulls significant current.... use that to test connections to see if they are decent connections that a metered ohm test may not pick up unless loaded heavily as with a headlight) ..... yes i know.... in the past i argued with simon that a headlight was too much for some of the small wires in the harness. i did some calculations later and realized that the current wasnt all that excessive, especially for a short term test.

Brian

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Does the deoxit contain a silicone? It appears to be tough to get here in the great white north.

I agree with the test under load you mention as pure ohm test can be misleading at times.

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Originally Posted by 2.216VTurbo

How does the headlight load test work? I read what you wrote and I sorta get it, sorta;)

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you unhook the components that the wiring feeds, then you use jumper wires to route 12v or ground through the wires to feed a headlight bulb to put 55/65w through that wiring. it exposes bad connections via the headlights light output.

like if you have map sensor issues and all else checks out, unhook the LM or SMEC connectors and the map sensor, hook the headlight directly to ground and send power through the map wires from the 60way or LM connectors to the appropriate pins on the map sensor plug to see if there are wiring faults. of course if testing sensor ground or sensor 5v power, youll need to disconnect all the sensors so you dont destroy them with 12v or ground on the wrong pin.

its useful for checking grounds and things that get fed through multiple connectors that may be in need of corrosion maintenance.

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Originally Posted by chromguy

Does the deoxit contain a silicone? It appears to be tough to get here in the great white north.

I agree with the test under load you mention as pure ohm test can be misleading at times.

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not sure. the MSDS sheets dont indicate silicone but they say its hazardous. i use deoxit D5. its safe for plastics and stuff like switches in old stereo equipment.

Brian

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Originally Posted by Force Fed Mopar

x2, did you do this?

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Need to pick one up from autozone. UPDATE:Swapping injectors didnt do anything

how is it that you're sure the valvetrain is ok and hasn't chucked a follower ?

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Originally Posted by Dr. Johny Dodge

how is it that you're sure the valvetrain is ok and hasn't chucked a follower ?

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I didnt see anything unusual when I pulled the v/c. I was first to check the lifters and make sure one wasn't cracked. Wouldnt I hear something? Im trying to pull the head only after ive exhausted every other option.

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Originally Posted by tryingbe

Compression test?

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90 in each cylinder.... seems low? What should I check specifically? Not seeing any weird smoke.

Sent from my HUAWEI VNS-L23 using Tapatalk

14-15 near sea level is really slow. I'd say double check the cam timing using Gary's way.

http://www.thedodgegarage.com/timing_belt.html

I had a similar issue a number of years ago, all of a sudden I had a cylinder come on and off. Checked and replaced everything I could think of, compression was good etc...Decided to remove the valve cover for the third time and used a long screw driver to compress the valve springs. Found a broken on on the intake side. It was very difficult to see but was super easy to compress. Swapped it out and good to go.