Hard Start in 96 454. Please Help, this is a doozy

[VorTecxas]

And I posted in your other thread, but I'll repost here. Your S1 O2s are fine voltage wise, they jump around when in an open loop. The B2S2 seemed high and may be bad, but that won't affect fuel trim. What it COULD be telling you is that you have a clogged cat, which WILL affect driveability. Your timing looks fine, but IAT seems pretty high. Our MAFs don't have a big response to temps, because (unlike LS1s) we have separate IATs that do it for them.

 

[orphan40]

I have a hard time believing worn dizzy or timing chain with only 65k miles.

Your mileage may vary. lol. I had a friend purchase a 76' bronco a few years back from the original owner with only 38k on the clock. That thing was trashed. Not a whole lot of it was usable. "Why", you ask? Because it was purchased brand new and ferried out to an island and used as a hunting/mudding/running through trees truck. He got it after it was retired. 65k may not sound like a whole lot, but the previous owner may have sat in his driveway bouncing it off the rev limiter for 6 hours a day to piss off his neighbors. You never know. lol

 

[454cid]

Stock injectors are 19lbs. Those 24lb injectors should be overfueling the engine unless you've got a custom tune. I don't know what a Superchips tune is like......if it's some one size fits all thing, that may not be good enough. Plus this 3-bar, 4-bar thing has me wondering. I thought the 454 was a 4-bar, just a few pounds lower than the 350........ not sure where they come up with 3 and 4 bars, as that is a unit, just like psi, and the 3 to 4 jump is a lot more than the few psi difference that I recall between the 454 and 350.

 

[brycebba]

Yeah the superchips only has a few programs and I run on the performance program. If I recall, bar is a measurement of pressure in atmospheric units. So I think 4 bar is somewhere in the high 50s or low 60s and 3 bar is around 45 or 50. I agree that it seems like it should be over fueling but based on plug coloring it is still lean. I bought a 350 fpr but I'm just trying to convince myself that it's worth a shot. I will probably put it in in the morning just to try it out


- Bryce -

 

[brycebba]

Put the fpr for a 350 and checked the distributor gear this morning. The distributor seemed to have little wear and the teeth were looking close to pictures of new ones.

The new fpr has a running pressure of 53 psi and it runs great. I'm interested to see what the plugs look like.

Unfortunately it still has a hard start problem. Unfortunately I forgot to write down checking the timing slack on my list so that didn't get done.

Pros to all this, truck runs great. Problem is that after all this I still have a hard start haha.

I haven't been able to check this but will let the truck sit for a bit and then just give a little throttle and crank it to see if that helps starting.

Is this something that could be related to a vacuum problem? Maybe a leaking egr or something? Or that solenoid next to it that vents into the charcoal can? I guess I should really pull the throttle body and give it a really good cleaning just for good maintenance too

- Bryce -

 

[454cid]

I thought 350s had a higher pressure than that...... like low 60s?

 

[SAATR]

I read most of the thread and there was no mention of cleaning or changing the IAC. I would clean it and perform an idle relearn on the ECM and see what happens. Barring that, it may just need a new one.

Sent from my XT912 using Tapatalk

 

[brycebba]

It primes to like 62 psi and then comes down some from there on mine. IAC is the sensor in the intake tube before the maf right? How do you do an idle relearn?

- Bryce -

 

[SAATR]

No, it's on the throttle body. It stands for Idle Air Control motor, and is what actually meters air around the throttle blade to set and maintain idle speed on the engine. Look it up on RockAuto and you'll see what it looks like. It's held on by 2 bolts, and the passage gets dirty and clogged by the same vapor and film as the throttle body. The relearn will require a scanner that can access OEM tests like the MODIS, Genisys, Tech 2, and some AutoXray scanners. After it resets the computer will vary the IAC pintle position until it finds its desired minimum and desired idle speed. It will nor want to idle initially, and you have to drive it to give it time to relearn.

Sent from my XT912 using Tapatalk

 

[brycebba]

Oh I see. I didn't take that IAC out but I recall seeing the part that looked like that when I pulled the throttle body off to clean it. It is was really clean when I put it back together but that doesn't mean it is working properly.

I don't know anyone with those tools so I will have to call around to see what people would charge to trigger the relearn. Is there a way to test that sensor?

- Bryce -