Foxbody hard crank/surging idle Issues Continue
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- เผยแพร่เมื่อ 8 ก.ย. 2023
- My ‘87 Fox doesn’t want to start without help or idle smooth after it’s warm. It starts up quick and idles smooth for the first time of the day but any attempt to start it once it’s warm is a pain in the butt. I think I’ve figured out the issue.
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Hey.. i have a 1989 Mustang GT.. been street/stripn 34 years.. I think i saw your issue in your last video.
Try to turn your hard stop idle screw up until your engine will Run with your IAC unplugged...raise it after your no run condition till it runs...see if it will stay running...if so..turn off.. reset TPS...then plug up IAC..and Restart.
I think you dont have enough throttle blade opening at idle..and its making the IAC chase its tail..and A9L is trying its best to trim and Add fuel to the YoYo idle.
If its better..unplug Negative Battery...for a bit to reset Long and short term fuel trims to relearn....then see how it starts again.
Ive always set the TPS..to .90 leaving a little room away from tip in.
If your throttle setting goes up above 1000RPM with IAC...and sounds like its in Tip-In..(not idleing)when IAC is plugged back in...throttle hard stop is too high.
850ish is a Good idle to taste.
Often when your idle is right..youll get a little throttle burble when the IAC is plugged back in..if while running..but i prefer to shut it off...because we are teaching it New manners.
Ill keep watching...to see if this Helps you or anyone else.
P.s. if this doesnt help...borrow a Known GOOD comp to try.
Good luck 5.0 Family.. :)
Thanks for the message. I tried your recommendation and I did get it to a point where it starts every time now. The idle surge is a lot better but not completely gone. My idle is just under 1000rpm to get it though. I readjusted the TPS but it has to idle high in order to get it to start when its warmed up. I don’t think the throttle body plate was the problem but it has helped the symptoms of whatever is wrong. My gut still tells me it’s either the IAC or MAF. I’m still working on it. Thanks for the tip and getting me in a better mood when I drive it.
Bad capacitor in the computer on the fuel pump relay Circuit could be failing. That is my guess. If your fuel pump and relay are good.
I can’t wait to see what turns out to be the problem.
Follow the base idle reset instructions on muscular mustangs.
I feel you brother I hope you can fix it😎
I had an issue with my Pro-M. Had much better luck with the C and L brand mass air. Shielded the filter from the fan wash.
Following along because I have the same issue. Mine started after having new cam, injectors an injector harness installed. I’ve been getting closer through tuning with old school Anderson pms. I learned out idle and adding timing at idle and fuel at startup.
Surge sounds like a vacuum leak
I thought the same thing also. I performed a smoke check in a previous video and didn’t find anything wrong.
@@thefoxlife3431 in another comment I left you a website that has a checklist to go through to try and figure out the exact problem you have. Smoke machines sometimes will not show a small vacuum leak very well for instance on the back of my Edelbrock Rpm2 there’s a set of ports for vacuum and I had one of those completely off one time and the smoke machine didn’t help me find it at all. It’s going to be simple and annoying when you find it but from that point on when you see somebody with the problem you will be a hero
I do not have anything to add to the conversation, unfortunately. I’ve shared with you my issues/struggles in the past with a crank but no start issue on a hot soak. Always been a TFI or dizzy for me. I think at this point I would get another computer. If that doesn’t fix it then you will have a spare. If it does fix it then have your old one refurbished so you have a spare. You have a beautiful car , stay positive
I don’t have any suggestions for you, but they do make liquid electrical tape that you can use to cover up your holes after you finish piercing wires.
I had this exact same issue on my 92 coupe, I spent a few years chasing the issue with no luck. The only thing that made any difference was one of those air bypass plates that goes between the throttle body and IAC. This stopped the hot start surging but still had to hold throttle wide open to start when hot. I’m very anxious to see what resolves this !
Another idea is to check the capacitors for corrosion in the pcm
Did you keep the old cap and rotor from the distributer replacement? I had an MSD that was doing the same thing, check the points on the cap and rotor if they appear pitted or burnt that could be the problem.
I replaced it all at the same time. I feel like it must be related to the IAC or MAF but It isn’t as simple as just replacing those parts. Maybe computer or harness.
when was the last time you did a base idle reset?
I’ve done several Ofer the past few weeks. It drives great and the bucking is gone at low speeds but it didn’t help this issue.
I had the same issue put your stock mass air back in see what happens
This was a mass air conversion before I bought it. It didn’t come with a stock set up. I have replaced the old explorer throttle body with an accufab and the BBK MAF with a Pro-M. Neither change improved my current issue.
It Could be a bad Tfi module. often times when the module goes out the car will start from a cold start but wont start when the car gets hot.
Yeah, I thought the same thing and have tried three other TFIs plus a new distributor. None of them helped this issue. This is my 4th video highlighting different things I’ve tried. I think it’s either the computer or wiring and those are really frustrating to solve.
Mine turned out to be the pcv valve.
Turn up the idle screw so it idles closer to 1000. 750 is more of the guideline for stock
I did that and it eliminated the no start issue but I don’t think that is the actual problem. It definitely helped the symptom but I had to set it at about 950rpm to work consistently. I feel like the failure is still likely the IAC or MAF but I’m still working on it.
@@thefoxlife3431 Never had a maf die on my 89 for over 10 years of daily driving, iac can cause issues try a motorcraft unit if you haven't already
@@thefoxlife3431 did you unplug the salt and pepper shakers at the rear of the intake and clean the connectors?
Maybe try opening the throttle plate more then readjust the tps to .9 volts. Seems like it's fighting from insufficient air
I did consider that also. I tried to open it up more and reset TPS but it didn’t help. I had my RPM idling at 1000 but it didn’t help the start when warm.
Do you have an A9P or A9L
I have an A9L and I had it tested and rebuilt in April by FoxResto. I kept trying to swap many other things because I didn’t think the computer could be the issue. Now I’m wondering if something did happen to it and it’s just bad luck/timing.
TFI module
Last video
I ended up figuring out the issue in a later video. It was ultimately an issue with the computer. Not the typical capacitor issues but the ROM chip was over heating. I had to get another computer and then it started fine.
I am chasing the same type issue, except mine is exactly opposite. Lol