Ruby misfiring/not firing on cylinders 3 and 4

[A_J_T]

Went out grabbed some dinner, car was parked on a steep street facing down the hill for approximatly 30 minutes. Came back stoked about the burrito's we just scored only to start the car and lumpy lumpy idle. it got me home and during the drive back it appeared to cruise ok on all 4 but entering boost it would surge and carry on. by the time i was home its running on two.

 

What i know

• Two rear cylinders 3&4 are misfiring
• There is spark happening on all 4 coils
• I dont have a fuel pressure gauge but i did try another reg
• Timing is set correctly
• No CELs

 

I'm going out, i expect a solution when i get back

 

Cheers all.

 

Edited October 8, 2016 by A_J_T

[Guest]

I run funny on burritos too. Get mcdonalds next time.

 

How do you know its missing on 3/4? What are you pulling the coil or injector plug?

[A_J_T]

Start the car and it only just idles and sounds like its on 2. unplug the two rear coils and nothing changes. unplug any on the two front coils and it dies.

 

havent touched injectors yet.

 

oh also have Tested the MAF and its working.

and there is a big black soot mark on the back wall of the shed which is about 1 meter away from the exhaust tip.

 

Wideband sits at at 14.# on idle and when reving up on those two cylinders so seems to be lean when gas on which made me think FPR but idk

Edited October 8, 2016 by A_J_T

[Andy_Mac]

Hmmm. Don't think she's getting enough air in, better buy my turbo, more boost solves all things 

[KwS]

Sounds a lot like my car when a coil was dead. Can you swap the front coils to the rear, and see if it follows them?

[A_J_T]

29 minutes ago, KwS said:

Sounds a lot like my car when a coil was dead. Can you swap the front coils to the rear, and see if it follows them?

Yea that was one of the first things i tried but 3 & 4 remain the ones offline. issue does not follow the coils...  it’s odd. popped all 4 coils and all of them have spark tried rotating spark plugs also, then bought 4 new ones cause it’s probably that time anyway so those will go in tomorrow at some stage.

 

What gets me is it was fine, then parked up and came back and it was all over. that’s what made me think maybe the timing tensioner had lost the plot and it had skipped a tooth on a cam gear when i started it but from what i can tell the timing is fine and the belt seems to have the correct tension so ehh

 

[A_J_T]

4 hours ago, Andy_Mac said:

Hmmm. Don't think she's getting enough air in, better buy my turbo, more boost solves all things 

haha phhhff this guy here, no respect!

 

although now that its in bits all over the landlords shed its probably a good time to throw in some TS headers and other bits n bobs.... But if its broke then that might be counterproductive

[1randomkiwi]

Oooooh mate
Not good. Time to plus t an ez and drop it in?

 

[A_J_T]

Compression Test results.

    
                  front of car
                         |  |  
_____________________________

#2 = 155psi       #1 = 135psi

#4 = 125psi       #3 = 112psi

 

Granted results are not ideal but getting good oil pressure so some oil gets all up in them rings is tricky and cold engine so sure compression could be better but not convinced it’s the issue at hand.

 

Moving on, Injectors seem to all pulse with a multi meter attached. I can see them pulse while turning it over anywhere from 10v to 19v.

Replaced al 4 spark plugs and put it back together in the hope that whatever suddenly came would to the same and leave but nope. If I hold it at around 3k rpm it seems to run on all 4 with the occasional miss and AFRs sit at 11-12 which seems rather rich considering its sitting in vac. Also the garage smells like unburnt fuel and plenty of good smelling smoke lurking.

 

Next plan, pull the ECU and drop in another REV-D ECU to test? anyone got one lying around?

I get the worrying feeling that I’m just missing something super basic, if you have any ideas just throw them out. I’m not going to jump up and down and say I already tried it haha.

Cheers!

 

Edited October 10, 2016 by A_J_T

[Guest]

Did you switch out the afm? Swap injectors? You have a cable yet?

[A_J_T]

22 minutes ago, evowrx said:

Did you switch out the afm? Swap injectors? You have a cable yet?

Bloody hell, no i didn't try swapping the injectors this evening this is why i need reminding haha spent all my time trying to check the leads to the injectors and didn't physically swap them.

 

Yea i tried another afm, and without it connected which throws a CEL but should still run fine.

 

Going to check timing again after ^ injectors cause yea all the cam gear marks line up but i never checked the crank gear cause its a pain to get to but think its worth a peek at this point.

 

No tactrix yet

 

Cheers Clint.

Edited October 10, 2016 by A_J_T

[Guest]

Im no good with diagnostics i just change engines and turbos and hope the problem goes away.

[A_J_T]

ALTERNATOR!!!!

 

Edited October 12, 2016 by A_J_T

[Guest]

Oh i actuallt thought that but didnt want to sound really stupid. Ive got two if you want one. Both allgood and cost you nothing.

[A_J_T]

 

 

21 minutes ago, evowrx said:

Oh i actuallt thought that but didnt want to sound really stupid. Ive got two if you want one. Both allgood and cost you nothing.

Haha you better be messing with me,

 

9v coming off the alternator. start the car without the alternator and she purrs on all 4 like a champion. connect the 3 wire plug and cylinders 3 & 4 stop firing  i'll probably pick one up tonight down here as i need it sorted to get up there, but cheers anyway boss.

[KwS]

at least its an easy fix!

[A_J_T]

Confirmed, replaced the alternator and everything is beautiful. charging 14v and running on all 4. 

 

I cant edit the title but if someone with permission to do so, feel free to change it to Google friendly/solved title.. idk 

 

Cheers all for the suggestions.