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

[brycebba]

Would the timing or a bad gear on the distributor react to ambient temperature meaning could they still be a culprit when it ran good in colder temperatures and crappy during hot? I pulled the plug after my mostly good drive this morning and it seems a little bit darker but not a lot. It was only 15 miles though. Im not sure how quickly coloring on plugs change. Did the O2 readings from the video seem within normal range for those RPMs?

Tonight I am going to try driving around while logging data and also see if I cant get my fuel pressure gauge rigged up with a go pro or something recording what happens with it. Any ideas in the mean time would be awesome

 

[brycebba]

I decided to just check all the plugs with some ac Delco ones I had and since some of the wires were crossed over I just put a spare set on. I also cleaned the maf really well. Idles great and doesn't sputter at all. Did I forget to mention that one plug had the ceramic completely cracked in half!? Still seems to have a hard start issue but as of now the other symptoms look to be under control.

- Bryce -

 

[orphan40]

It's not hard at all to pull the distributor. Pull the cap off and mark the position of the rotor to the distributor body. Then mark the position of the distributor body to the intake. Unplug the dist. Then crack the retaining bolt loose and slide the lockdown arm away and pull the distributor straight out. Check the gear and replace if necessary. When you put it back in, make sure all your marks line back up (remembering that the rotor will twist a bit as the dist mates back up to the cam). Move the lockdown arm back into place, tighten the retaining bolt, plug the dist back in, and put the cap back on.

 

[brycebba]

So knowing what I know now and that it runs good just hard starts, could the distributor still be an issue or would that cause problems all the time?

 

[orphan40]

I can only attest to the problem with the distributor gear. That is really the only problem that I've ever had with starting my truck. You've checked pretty much everything else except the dist gear and the timing chain. When I could get my truck to crank, it ran fairly well with a bit of hiccuping.

 

[brycebba]

ok good to know, it could still be a culprit then I guess. You cant screw up the actual distributor when you do a cap and rotor can you? I did those and I hope I didnt do any damage

 

[skylark]

Your problem is with ambient temperature. The mass air flow sensor should have an air temperature sensor in it. Just for grins when it hard starts, unplug the maf and see what it does. Unplugging it will throw it into its speed density base tune. The other problem that I would check is that you are getting a true 5v reference to the sensors that require it. I would also check for 0 ohms on the ground side. Check all of them don't just assume that they all are good.

 

[brycebba]

before the plugs and thorough cleaning I did that, it started and then died. I want to try it again tonight and see though. As far as I understand the sensors generally send more fuel when cold and less when hot at start up time. Would it be helpful to wait the amount of time that it normally takes to reproduce the hard start but put a bag of ice across the MAF and air temperature sensor and get intake temperature really cold? I would think that if it fires right up then I would know it has something to do with that temperature being recorded or interpretted and if it responds the same then maybe it doesnt. Makes sense to me but I may be misunderstanding how this works.

 

[skylark]

That would take awhile to cool the whole sensor. You might be better off with a couple of small bags in the bottom of the air box and a fan sitting by the passenger side headlight area to try to cool the incoming air.

 

[skylark]

On second thought, a can of the compressed air used for cleaning keyboards and such could be turned upside down and a quick blast at the temperature sensor might give a more dramatic effect.