2G No spark on 2 and 3

[Pjj]

Good morning guys, having a bit of an issue, I know its probably been talked about before. 98 GSX 7-bolt using 7-bolt 98 harness and sensors and I'm not getting spark on cylinder 2 and 3. I am getting spark on 1 and 4, laid the plug on rocker cover and physically saw it.

The car has sat all winter, put a trans in the car and moved the harness around a bunch. I tried another set of coils and its doing the same thing. I also tried another PTU, same thing. I'm leaning towards maybe a CAS or crank position sensor. Any thoughts?

In DSMLink, is there a way I can tell for cam or crank sensor? When I tried firing it the rpm would jump on the log.

also want to make mention i did extended my CAS wiring, i did it properly, i soldered each wire individually and put heat shrink over each. also replaced my coolant temp sensor pigtail and wired it in correctly.

 

[curt-s]

Have you checked your plug itself for any broken contacts?

 

[Pjj]

it was getting pretty dark last night so ill be going back in tonight to check. i have the coil packs bolted to an aluminum bracket on the back of the block so i gotta jack the car up and reach in from underneath to get to it

 

[dwb]

Do you have a check engine light?
Sounds like power transistor to me, but you said you already swapped that. Did you check for corrosion in the connector when you swapped it?
Might be worth looking into the coil pack too.

 

[chrisman287]

Check the PTU harness I had a wire that was 99% broken and hanging on by a thread. Give them a slight tug make sure they’re solid

I would go over your CAS wiring that you did as well. I don’t like soldering I prefer to use non insulated butt connectors and shrink tubing

 

[curt-s]

https://www.dsmtuners.com/threads/how-to-test-the-power-transistors.229419/

https://www.dsmtuners.com/threads/cas-diagnosing-steps.238267/post-50470620

 

[Pjj]

Do you have a check engine light?
Sounds like power transistor to me, but you said you already swapped that. Did you check for corrosion in the connector when you swapped it?
Might be worth looking into the coil pack too.

no check engine light

Check the PTU harness I had a wire that was 99% broken and hanging on by a thread. Give them a slight tug make sure they’re solid

I would go over your CAS wiring that you did as well. I don’t like soldering I prefer to use non insulated butt connectors and shrink tubing

ill take another look, its soldered with heat shrink tubing over top. ive always done this and never had an issue

 

[luv2rallye]

The CAS determines which spark plug pair to fire (CPS determines when) so look at the CAS and it's wiring. CAS sends signal to ECU which drives the PTU which drives the coil which drives the spark plugs.

 

[Pjj]

So last night I literally had 5 minutes to work on it, so I swapped my other CAS in and nothing. I'll have more time to work on it tonight so I will fill you all in with my findings tomorrow night.

Hopefully I can fix it.

 

[curt-s]

Have you tried swapping the coils arounds? Move 1&4 to 2&3 and vice versa, change the wiring on the pack and your plug order

 

[Pjj]

i tried a whole different coil pack, but i believe i tested the 1-4 by accident. ill be swapping them all around inspecting pigtails etc tonight

 

[Pjj]

so we now have spark, when i was removing some wires from the harness i accidently nicked the wire for the blue pigtail that sits along the firewall that controls ignition. but it still is having a hell of a time to start. im getting spark on all 4, fuel on all 4, and it LOOKS like were getting airflow on the log. checked compression on the car last year and it was 176 across the board. any ideas?

 

[Pjj]

RESOLVED:

so once I got all spark on all 4 I knew it would be just a matter of time before it would run again. So last night I was working on it, had spark, fuel, compression and air. Was stumped why it would just crank and crank and crank and MAYBE run for one second then die.

Today after work I put a brand new set of spark plugs in, half a tank of fresh fuel with a thing of octane booster, made sure there was good contact with the plug wires, boosted the battery and boom the car fired right up. I don’t know exactly which one of those that were causing it not to run but the combination did and quite frankly I’m happy with it!

 

[curt-s]

Don't forget to make your offering to the DSM gods. I hear they take timing belts and thrust bearings as sacrifices.

 

[TerminalTalon]

It was probably the cranking amps and voltage of the battery but the plugs were probably fuel soaked also.