Foxbody hard crank/surging idle issue when hot Part 3 (spark, air, fuel or something else?)
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- เผยแพร่เมื่อ 5 ส.ค. 2023
- I’m still at it and trying to figure out this crank no-start when hot issue. This ‘87 GT is really giving me fits. It runs great until I turn it off, then it’s a crap shoot of how long it takes to start again.
I just amazed at how calm and patient you are going through all of this!!!
Ha, thanks. You should hear me when the phone is in my pocket. 🤣
@@thefoxlife3431 oh trust me…I know lol.
Vacuum leak. The module on the distributor change it $50 MSD.
I’d check TPS voltage to remedy the surging when it starts
Thanks for the reply. I’ve made a few different videos on this issue and I did try a different TPS and I also verified 0.98v and performed a couple base idle reset procedures. No luck yet.
You have an IAC problem. It can't control the idle. Unplug the one on the engine and plug it into one of your spares. Start the engine and watch to see if it is moving at all. If the Spare IAC isn't moving, then you may still have an ECU problem.
Also, I have seen a lot of aftermarket MAF's that aren't very good. With the larger injectors, the MAF has to fool the ECU into thinking the injectors are stock size. It's a band aid at best. The correct way to do it is to get a custom tune with a chip.
Ect sensor tells the computer the engine coolant temperature. If the sensor is bad it can tell the computer the coolant is at 0 degrees the computer will keep the fuel trims extremely rich since it thinks it’s 0 degrees outside. The car will not Hott start as it’s flooded with fuel because of the bad ect sensor.
Anytime you’re checking wiring instead of checking for continuity just do a loaded voltage test on each wire suspected. Apply ground to one side of the wire, connect a light bulb to the other side and shoot power to the other side of bulb.a good circuit should light the bulb bright and show battery voltage on the positive side of bulb and ground on the other side . This indicates a good circuit. Checking continuity only tells you if there’s a connection in the wiring but will not tell you off the wiring is damaged and able to carry a load.
I’d suggest checking the connection at the salt and pepper connectors or the extension harness if it has it. Next I’d check pin 37 and 21 on the computer.
Not sure if anyone had suggested this previous. Good luck
Thanks for the note. I do not have the extension harness. I did clean the pins and spread them out a little with a straight awl. I am not in the mode of checking various circuits at the computer. I’ll add your suggestions to the list. I’m going to check pin 50 and 9 for voltage and resistance next. Thanks.
Not to beat a dead horse BUTTT..
The ect sensor has a bearing on the iac input.
Ive been sold the wrong ect sensor more than once. A lot of the parts chain sensors try to fit a range of vehicles and sometimes their "cross over" chart is inaccurate.
I’ve got the various ohm readings to look for at different temps. I’ll try to test it instead of buying another sensor.
I have a 91 doing the same thing. also mild; 306 with e303 cam, gt40 heads and gt40 tubular intake. About 7 or so months ago I stripped it down to a short block and rebuilt the motor and replaced every sensor and sending unit (minus the low oil sensor; i guess i just over looked it) with brand new ones. I have driven it plenty since and its been pretty good to me. There were, of course, minor kinks after the rebuild but nothing this bad. It only started doing this to me about two weeks ago and It’s been toying with me since. Im only 19 so I still have a lot to learn about these things and still cars in general but it does make me feel better to know I’m not alone. I hope you figure it out, it’s a bummer having something so fun and not be able to enjoy it.
My my car is doing the same thing🤯
I haven’t figured it out yet but I think it might be my MAF wiring. I’m still trying to diagnose it.
I have same issue! When hot, I pedal it to keep it from surging, then it settles down and runs well! Just drives me nuts!
Gotta see what your fix is!!
I’m still working on it but should have another update this week. I’m looking into the MAF and wiring now.
Hi bro, I have had the same exact problem with my 1990 mustang for so long, were you able to fix yours? If so what was the problem it had? Thank you and God bless.
It’s an ecu ground wire problem there’s a smaller wire the ecu ground to the chassis so it can use the body grounding to read the 5 volt sensors
TFI module. Back in the day a person would have a spare one in the glove box
Also. A vacuum line by a heat source can cause the vacuum to lose pressure
My 88 coupe does this exact same thing but when its cold. Once its warmed up its perfect ive done base idle reset and it helped a bunch however now and again itll do the idle search thing when its cold or first start of the day. Its frustrating. Good luck..
I must have misunderstood your last video 🤔 I thought you was having a no start issue.🤔 but after watching this video I see that's not the problem.. your engine does start. it just idle hunts and you have to throttle it a little correct? have you try the
( ECT ) coolant temperature sensor? That sensor is very important! the ECU needs the ECT to properly adjust air/fuel and timing.
In this video, my car had run as long between the different scenarios. It started a little easier since it wasn’t as hot. It’s always been an issue with needing multiple attempts to start once it’s hot. The idle surge has also always been an issue once it gets hot. I’m pretty sure it’s the IAC circuit. I found an article that says one wire should be +12v constant and one should alternate from 0.5-12v. Mine doesn’t fluctuate and it stays at 13.8v. I’m going to i vestige circuit #21 on the computer.
Gotta agree this is a tune issue more then a no start, the car doesn't want to hold an idle... I would pull the spout next time it happens just to see if removing the computers control of the timing effects it at all. ECT is also a good sensor to check if the computer thinks its cold.
I had the same problem and it turned out to be the brand new China made distributor. So, I replaced it with a genuine Ford rebuilt. Good luck finding genuine rebuild now a days or you can rebuild your own.
Been waiting for this video. Watching it now. Very curious
That’s the same “hot forged” dizzy that failed me about a year after installing it. The stator kept cooking TFI’s when it got hot
So I’m very curious
I have noticed that it does get pretty hot. I may try a TFI relocation kit in the future. I don’t think it is the cause of my current issue though. It’s looking more like a wiring harness or computer issue with the IAC circuit.
It's your idle control sensor😊
I think the actual IAC valve is ok but the signal from the computer seems to be the issue. I’ve ruled out the injector harness so either the main computer harness or the computer has an issue.
Can you start the car with the IAC unplugged? does it still surge with no IAC plugged in? I have not watched the previous videos... you did the whole base idle reset thing everyone talks about?
I had mine sitting for 4 yrs and decided to put a battery on and it turned right on then i did a full tune up and drained the gas to put new gas in it took it to the gas station and got back home now it wont turn on just cranks
Ect sensor controls cold start, Hott start fuel trims. My full size bronco wouldn’t hott start the sensor was bad. Engine coolant temp sensor.
Yeah, I did change that a few weeks ago because it seemed to make sense with the symptoms. It didn’t help in my case. I also change the air charge temp sensor.
@@thefoxlife3431 their is an ohm test of the sensor...test the Chinese parts...
Just go through the cranks, no start checklist, methodically on stangnet. Run a KOEO and KOER test and go from there.
Okay I'm having the same problem but it's only the first start of the day when it's cold and I've done just about everything you've done.🤔🤔🤔🤔
Did you change the IAC? I’ve read it will cause a no start when cold also.
@@thefoxlife3431 my iac work's just fine.
tps maybe
never mind see you tried it
Hi check your ground wire I notice that wire is missing on body but change the terminal on the battery put it back at the original wire my did the same thing it was surging I clean battery terminal because the computer needs ground hope it work
Good eye. I have checked all the grounds and moved the one because the hole was stripped out and I wanted a tighter connection. I just moved it a few inches to another hole in the fender. I even added an additional ground from the block to the chassis, similar to how the SN95 did it.
GL, the Negative battery terminal also contains the ECU ground connecting to the battery.
@@ryandoyle4344what if my car ran good with that ECU ground wire connected to the chassis but not looped from the chassis to the negative of battery it was just curled up
Try putting on the Cardone cap and rotor.
So when it's hot its in closed loop so you my have a issue with the 02 sensors
I Han’s thought of them yet. They were replaced in 2020 but I’ll check them out. They are harder or more complicated to test if I recall.
oops i meant all new wires and connections.
how bout changing and putting "all new wires"/
Gotta be something in the computer
I’m thinking so as well. I will try to measure the voltage at the computer connector and see what I get. If it’s bad, I can return it to the folks that replaced the caps earlier this year.
Brew2l has a video on his buddies coupe he was having an idle issue and it was about the IAC circuit not working a wire had gotten pinched or broken or something between the ecm and the IAC right near the connector on the ecm side I think the video was a while back it's on a red coupe brew2l vlogs channel
Update?
I’m still working on it as I get time. I think it could be MAF related and I’m slowly working through testing the wiring.
Check out the torque on the starter replace starter?
Or your crank position sensor
Do you have a code reader
Yeah, I’ve pulled them a couple times but only get the standard codes from my smog delete.
Any chance advancing the timing is a possibility?
I actually lowered the timing from 14 to 12 but I didn’t have any changes in the issue.
@@thefoxlife3431 have you identified the cause yet. I have had that issue before. For me it was when I had the stock intake on my 94.. when I put a new bbk intake like you have.. it solved that. Is there a chance the maf in your intake is the cause?
Bad capacitors in the ecu?
I need to do a little more testing but I think it might be a computer issue. I had the caps replaced earlier this year but that doesn’t mean it isn’t the problem now.
TPS setting?
Thanks for the comment. It ended up being an overheating issue with the computer.
This is a tune issue not a crank no start, your chasing your tail throwing parts at it if your problem really is a hot idle issue. ECT can play a small roll when modified but mostly only when its close to stock and there not vaccum or exhaust leaks before the sensors. Not sure how the mass air swap was done or the total mods to the car. I can say I have never been a fan of bbk mass air meters. You best bet would be having someone burning a chip and work on a tune that will work for both a cold and hot start or step up to a better aftermarket efi computer. The stock ecu without A chip can only compensate so much with adaptive strategies and idle quality is one of the biggest issues when you really modify them. I've had bolt on junk to heavily modded strokers running on stocks ecu's without chips over the years but the ones with a decent cam and more radical upgrades had absolute garage idle and drive ability issues, the stock tune could not compensate enough to allways hold a decent idle. They all ran and drove fine but there was all ways large improvements in a tune.
Yeah, it starts on one crank when it’s cold and idles/drives great. Once it’s warm, like 5 minutes of idle, it will crank but hesitates to start unless I give assistance through the accelerator. It will then idle up and down for a while until it smoothes out. My engine s very mild. GT40p heads, E cam, RPM II intake, 24lb injectors and MaF. I didn’t do anything recently to cause an issue. It doesn’t have a chip and the A9L computer was rebuild in February. The last mod I did was a coil and distributor back in April but it ran fine after the change until a few weeks ago. I’m at a loss.
@@thefoxlife3431 bro it has to be that distributor I had some crappy one from the stores online. Just get an O'Reily's one or AutoZone one and try that see if it works worked for me
Check the computer. Take the cover off check for leaking capacitors....
I can’t take the cover and look because I had FoxResto rebuild it earlier this year. They place a seal on it and won’t warranty it if it’s cut open. I’ll likely put up with the issue until winter, if I don’t figure it out, and then send the computer back when I’m not driving the car. It’s a pain to get it started after it’s hot but I’m not ready to park for several weeks straight right now.
Omh test the ect sensor. Just because it’s new it’s still Chinese.
The module on the distributor change it $50 MSD
IT’s electrical not mechanical
You think it's definitely the wiring from the IAC sensor
Jesus dude you are wasting your time…do you have spark, get a spark tester out. What’s the fuel pressure? Is it tuned? Pull the codes. It’s probably a CTS but pull the damn codes.
Yep, I’ve covered all those topics in part 1 and 2 of this series. The sensors were some of the earlier and easier things to try but it didn’t fix the problem. Codes were ran at the beginning of this issue and nothing relevant came up. I’ve been using the StangNet info and showed part of it in the video. It doesn’t have a tune, just basic A9L. I’m pretty sure it’s the IAC circuit from the computer but I’ve got to pull the kick panel and test my theory.
Maybe the idle air control
I tested my IAC and even the original one that I replaced a few years ago. I(I’m a pack rat). The actual IAC is good but I think the issue is in the wiring or computer. Most likely the computer. More to come.
Vacuum leak