88 comanche hard start or no start when cold

[Ωhm]

5 hours ago, ctxj93 said:

It attempts to go into closed loop, ST Inj goes up to 255 and goes back into open.

When ST is climbing to 255 (CL), INJ PW climbs to 7.2mS, yet O2(V) stays at 4.08V (LEAN). Either the ECU is not increasing fuel, which it show it is or the O2S just doesn't register it (extra fuel). Video timeframe (0.23-0.26)

[ctxj93]

58 minutes ago, Ωhm said:

When ST is climbing to 255 (CL), INJ PW climbs to 7.2mS, yet O2(V) stays at 4.08V (LEAN). Either the ECU is not increasing fuel, which it show it is or the O2S just doesn't register it (extra fuel). Video timeframe (0.23-0.26)

Yes I noticed that. You would think with the 2 other values both showing increases and the rpm dropping a little, that something is actually happening with the fueling.  I installed a fresh set of reman 746 injectors, (it acted the same way before the swap) and also a full Jeepcables 2 ga kit over the weekend.  I'll put an o2 in it tomorrow and see if anything changes. 

[fiatslug87]

You seem to be having the same issues as this: 

 

[ctxj93]

30 minutes ago, fiatslug87 said:

You seem to be having the same issues as this: 

 

Defintiely very similar to what he's  dealing with now, not so much in the beginning of the thread.  Mine ran/runs fine in open loop. No stalling no backfires. I've dealt with bad renix EGRs before I know how annoying that can be to try to drive. 

 

Edit: I see that an o2 sensor that tests in range is tough to come by. I guess I'll see if I can get the old one off my parts truck 

Edited February 4, 2021 by ctxj93

[ctxj93]

9 hours ago, ctxj93 said:

Defintiely very similar to what he's  dealing with now, not so much in the beginning of the thread.  Mine ran/runs fine in open loop. No stalling no backfires. I've dealt with bad renix EGRs before I know how annoying that can be to try to drive. 

 

Ok so after a new Group 34 battery. Jeepcables kit and 746 injectors this is the crank time.

 

Cruiser, this should be an apples to apples comparison to my last video. I let it sit overnight,  it was around 26 degrees this morning and this was a single key cycle. 

 

 

[ctxj93]

Ok I promise this is the last time I'll be responding to my own response. 

 

Swapped in a Bosch 12009 o2 sensor which showed 4.2 ohms out of the package. It did look different than what came out of it. The truck started right up, same as this morning and to my surprise went into closed loop and stayed there. I have an NTK 23553 on the way in case I have any issues down the road with the current sensor. 

 

Here's a video of the data stream, let me know what you think.

 

I'm also interested in any comments on my last start time video. I counted 4 or 5 seconds of crank time.

And for good measure, here's a pic from the fall of how it currently sits.

 

 

[Ωhm]

9 hours ago, ctxj93 said:

Ok so after a new Group 34 battery.

 

39 minutes ago, ctxj93 said:

I counted 4 or 5 seconds of crank time.

Gotta love a new battery with balls. I got about the same count in seconds.

 

Video showed RICH/LEAN switching, better MAN VAC reading. ST Fuel Trim finding whats right for your newly installed injectors. Once again the O2S is the boss sensor.

[ctxj93]

2 minutes ago, Ωhm said:

 

Gotta love a new battery with balls. I got about the same count in seconds.

 

Video showed RICH/LEAN switching, better MAN VAC reading. ST Fuel Trim finding whats right for your newly installed injectors. Once again the O2S is the boss sensor.

Thank you again for your help along the way. I guess I need to let it run longer and drive it to see if the LT fuel trim changes.  I know you said 3-5 sec would be considered a quick start time. Should I stop trying to improve it at this point? 

[Ωhm]

5 minutes ago, ctxj93 said:

Should I stop trying to improve it at this point?

Never, but now its time to take the time and enjoy the ride and let all them new parts get dirt on them. You got the tools, clean them up and put them away and hope you never need them again. 

[JMO413]

Good to hear you got it figured out. No need to ever stop improving as long as your enjoying the truck. 

[ctxj93]

Oh I'll always keep wrenching on these things. Defintiely an addiction! I just meant should I be happy with the current cold start crank time or keep trying to make it shorter still. 

[Ωhm]

For me 7-9 seconds is a typical cold crank start time. You're down to 4-5 seconds. You done good, but if you got ideas and can knock some more time off that, go for it. Keep us posted.

[ctxj93]

Put in a set of NGK 7373's today, seems to run pretty good. I took it for about a 10 min ride around the neighborhood, I have no plates or tail lights currently so I'm limited to a couple mile loop. When I got back I plugged in the brick and it was stuck in open loop, o2 sitting at 1v and exhaust reading rich. 

 

My NTK sensor had shown up so I put that one in and like everyone has said, it seems to work fine. Went out again for a similar hot lap with the scanner plugged in and everything seems to be functioning correctly. LT fuel trim dropped to 125 after driving it for a bit too. 

 

So the moral of the story is don't  be an impatient idiot like me. If the guy at Napa offers you the Bosch he has in stock, politely decline. Order the NTK off Rockauto and wait the few extra days.