Help with Heat soak/Hot Start

[JDL5.0]

As the tittle says I have trouble starting the car when hot. If it wasn't for a serious hot battery it would not crank. Walk away and let it cool down for 30 mins and it will fire right up. I have been working on this car more than driving it trying my best to get it all figured out and I am almost there but I need help please. Something I have changed or didn't change has caused this because it hasn't always been like this.

Car is a 92 5.0 LX Hatch with a 306 with forged internals, cam, aluminum heads and intake, big fuel system etc... and a max 6psi Vortech supercharger. There is plans for an inner cooler but not one yet so I am dealing with hotter intake temps than normal. I would like to add that when this car is running it is running great! Cold starts, idle with or without AC on etc...

I am adding my data log of a quick drive on a 91 degree day and then a Data log of actually trying to start it while hot and my current tune. Please help me learn and fix this tune please. I would love to drive this car more often without worrying if its gonna crank if I accidentally stall it at a red light etc...

Thanks in advance for any and all help!

 

[JDL5.0]

As requested I forgot to mention that the hard start is a real slow dragging start. Only does it when its hot and soon as it starts it runs perfect as if nothing every happened. I have heat wrapped and starter heat shield/blanket hoping it would help. Ask me anything to help you see the whole picture.

 

[Noobz347]

What makes you think it's a bad tune versus a weak/hot starter or cable or solenoid?

 

[JDL5.0]

Well I have been pulling my hair out getting the tune figured out and because the hot start started all of a sudden I instantly assumed it was something I messed up in the tune. Now that you have mentioned it, I am not 100 % sure of anything at this point. Here is what I do know. The starter is a high torque put on about 2 years ago and it was set up with a relay so the starter gets full power when the key is turned. Another car guy told me to do that. The starter doesn't have as much use as it does age. Is there a way to test it without throwing parts at it? I need to start eliminating possible causes before buying parts. I have extra cable left over from the battery relocate, I could run a new cable to the starter to see if that helps?

 

[Noobz347]

I'd take her for a drive and plan to get underneath it while it's still warm.

When you go to start it when it's hot, does it "click" at least but not roll over? What are the symptoms? Even the extra relay is s suspect depending on where it's mounted.

 

[JDL5.0]

It turns over. Best way I can explain it is say it needs to turn over at 1000 rpms to crank (again just example numbers) well when hot it only turns over at 7 to 800 rpms. Right there at it but just not quite enough to start. If you wait 30 mins give or take for the temp to drop just a little then it will spin fast and fire right up.

 

[Noobz347]

I think you have a starter issue. I had the same thing happen to my rig a couple of years ago. Aftermarket headers, mini-starter (brand new, in fact), etc...

I saw where you said you have the pipes wrapped and a blanket for the starter but unless you have some data that indicates that your engine is running lean then I'd say your issue is with the starter/wiring.

Is your mini-starter the kind with the reduction gearbox or does it look like a smaller version of the original piece (straight shaft)?

Can you roll it up on ramps after a good drive and feed the starter [all the onions] from a good battery and set of cables? This would tell you quickly if it's the starter or if the issue is upstream of the starter.

Reseat your engine ground cable at both ends too. It should also be a good size (I'm thinking 4 ga). You can also use a set of jumper cables to eliminate the ground connects as a problem by going straight from the ground post to the starter body (as a test).

 

[JDL5.0]

I am heading out of town in the morning and I don't think I will have the time to look at it this evening. I will get back on here soon as I look at it and report any change. Thanks

 

[General karthief]

Relocated battery you mention, DVM and voltage drop test the cables and starter.

 

[JDL5.0]

Yes I relocated it to the hatch with a battery box, disconnect switch, etc... and used all new 2 gauge cables and copper crimped ends. Why I didn't change the starter cable other than simply forgetting about it I have no idea. So it very well could be old, rotted and verily doing its job. Even the alternator cable is new so I don't know why I neglected the starter wire but I assure you I will fix that mistake very shortly.

 

[General karthief]

That will have an effect on your membership dues

 

[nickyb]

I had same issue on a gm product with battery in trunk, turned out my fairly new starter was fubarred.
I waited till summer was over to change it, did it in the streets back then.

 

[from6to8]

lol I am going to check and maybe swap out my IAT and ACT sensors on my 95. I have a few other car/engines that I'll try swapping first and see if that helps my issue. What mine is doing and I think the problem went away some years ago and can't remember what exactly I did because after the car got hit in 2015 I the engine/car sat until I put it in my 94 Cobra in 2021.

What it will do and I swear it's only on extreme extreme hot days and likely after I've driven for say 15 minutes or so. If I stop at a gas station per se and shut the car off to get gas and go to start it, it will start fine but if I don't give it gas/keep playing with the pedal until I take off out of the station's lot it will cut off. It will start fine every time even if the car shuts off 5 times in a row. I can leave the station and go to a red light maybe 1/4 of a mile and usually it will be fine and stay running until I shut it off again. I think it's sometimey as to doing that even on hot days as to taking off and getting to a red light within say a 1/4 mile or so. I did notice the last time I drove it well the time before the last time, when I went to take off after stopping for the first time (I think I shut the car off at this one station but didn't get fuel can't remember). But when I left the stop sign the car started sputtering some when I took off only did that for few seconds. I drove about 30 minutes and stopped and got gas filled it up and when I took off from a stop it sputtered again for few seconds but didn't do it the rest of the day nor the next time I drove it.

 

[manicmechanic007]

I agree with checking the starter for amperage draw when hot and the condition of the battery when hot
Unless you have 25 degrees if initial timing hot, the tune is not your problem IMO

 

[CAMTWO1070]

The only times Ive ever heard of such things happening is when the TFI or the distributor pickup module is wrong or going bad or the TFI distributor isnt grounded good in the engine block or the battery has a dead or weak cell.

When you look at the wiring for the TFI module youll see one wire is labeled 12v start....

Id probe that wire and see if its giving the right amount of power when the key is thrown because that wire when power is applied retards the timing.............

In my wiring harness I have the wire removed from the wiring harness and relocated it to the starter activation wire that triggers the starter solenoid..

When you look at this pic on doing a TFI module test notice theres a test that involves the grounding plate that mates with the distributor called distributor base and is supposed to have cooling compound between both to transfer the heat.

When the thermal compound gets hard and crumbly the TFI module loses its ability to properly transfer heat and causes the TFI module to fail..



Another thig I found out is that cast iron distributors bleed off and retain less heat than billet aluminum ones...

And a simple device like this stops the TFI module from being heated up from the engine block and waterpump when youre relying on just an electric fan..



Good Luck

 

[from6to8]

The only times Ive ever heard of such things happening is when the TFI or the distributor pickup module is wrong or going bad or the TFI distributor isnt grounded good in the engine block or the battery has a dead or weak cell.

When you look at the wiring for the TFI module youll see one wire is labeled 12v start....

Id probe that wire and see if its giving the right amount of power when the key is thrown because that wire when power is applied retards the timing.............

In my wiring harness I have the wire removed from the wiring harness and relocated it to the starter activation wire that triggers the starter solenoid..

When you look at this pic on doing a TFI module test notice theres a test that involves the grounding plate that mates with the distributor called distributor base and is supposed to have cooling compound between both to transfer the heat.

When the thermal compound gets hard and crumbly the TFI module loses its ability to properly transfer heat and causes the TFI module to fail..



Another thig I found out is that cast iron distributors bleed off and retain less heat than billet aluminum ones...

And a simple device like this stops the TFI module from being heated up from the engine block and waterpump when youre relying on just an electric fan..



Good Luck

I was reading @Mustang5L5 post about his issue I believe the title is help with hydroboosting. It seems his issue as well as mine on my 94 which has the TFI module on the firewall, he has a fox though, but our issue definitely seem to be only when it is extremely hot and humid as to when ours want to act up and do that. If our cars are running super rich in those times then a tune likely won't fix it if it's running fine the other times correct? Unless the stator (pickup in the distributor gets to hot under those circumstances and cause that issue?

 

[JDL5.0]

Thanks for all the replies, I have not had time to get back to the car where I have been out of time. I did find out that my tune was bad, way off for initial start ups. Hey manicmechanic00 its funny you should say that because that is exactly what was going on. 25 and then some. The only thing I can think of is during the winter while I was fine tuning cold/freezing starts I unintentionally changed the settings for the hot starts. By pure luck I founder a tuner that was willing to live tune if I wanted to BUT he took a quick look and smoothed out some fueling tables I had and then pointed out my timing table on start up was way off (way to high). I have his tune ready to upload to the car but again I have not been able to get to it. I hope to have this done by the week end and will report back.

​

 

[manicmechanic007]

Wonderful, the car is fine then, and just the tune needs looked into
You were right and yes learn to tune it yourself
Buy the dedicated laptop and whatever else you need

 

[JDL5.0]

Wonderful, the car is fine then, and just the tune needs looked into
You were right and yes learn to tune it yourself
Buy the dedicated laptop and whatever else you need

Learning to tune it myself has been the hardest on my own thing to do. Most of the forums treat me like I am bothering them IF they even respond so I spend late nights on line searching for any little bit of help I can find. I came across a year old video of a guy raving about this tuner that helped live and gave a shout out to him. So I figured its worth a try, emailed him and sent him data logs and my current tune. About three days later (I had already forgotten about him) I got an email from him, he was very kind and helpful. Like I said he told me his prices if I needed him but he went ahead and took the liberty of smoothing out some of my tune and fixed my timing issue. I offered to pay for him taking the time to even look at my tune and he said not necessary. I feel like that will def fix my issue BUT since the power cable going to the starter is still the original and every thing else is new, I am going to replace it as well. Peace of mind.

Side note--If any one has a tune issue that no one can figure out let me know and I will give you this guys email. I didn't put it on here because some times forums see that as advertising or something like that. I don't want to break any rules. It might only be fore Megasquirt though, not sure about Holley etc...

 

[from6to8]

Learning to tune it myself has been the hardest on my own thing to do. Most of the forums treat me like I am bothering them IF they even respond so I spend late nights on line searching for any little bit of help I can find. I came across a year old video of a guy raving about this tuner that helped live and gave a shout out to him. So I figured its worth a try, emailed him and sent him data logs and my current tune. About three days later (I had already forgotten about him) I got an email from him, he was very kind and helpful. Like I said he told me his prices if I needed him but he went ahead and took the liberty of smoothing out some of my tune and fixed my timing issue. I offered to pay for him taking the time to even look at my tune and he said not necessary. I feel like that will def fix my issue BUT since the power cable going to the starter is still the original and every thing else is new, I am going to replace it as well. Peace of mind.

Side note--If any one has a tune issue that no one can figure out let me know and I will give you this guys email. I didn't put it on here because some times forums see that as advertising or something like that. I don't want to break any rules. It might only be fore Megasquirt though, not sure about Holley etc...

I have in my notes a guy that does remote tuning and also along the lines of he sends you a tune then you drive the car and report back to him and he makes changes. Not sure if I'll go that route with my 351 build or just get a dyno tune. Since I'll likely want to dyno it as well I might just dyno tune it and be done. The car won't receive any changes as whatever I get it'll stay on the car a minimum of 5-10 years if not forever lol so I think i'll be fine.