Crank and sputter but no start

MaxR830

Registered User
Hello all,

I'm new to the super coupe gang and just recently bought what is turning out to be a lemon 1991 thunderbird super coupe. It cranks and sputters like it's trying to go but won't start, it will also stop cranking and all lights will go out for a split second almost like cranking on a low battery but the battery is new and charged, then go right back to cranking. Here is what I've replaced. In this order.



Plugs

Idle air control valve

Coil pack

Fuel filter


Cam positioning sensor - When I replaced this it ran for about 3 minutes then died.

Crank position sensor - When I replaced this it ran perfectly for about a day then I noticed the tach would drop off and the check engine light would come on but the car would run fine. Then after a few minutes the tach would come back. Then I went to start it one morning it would crank and sputter but not start.


New DIS module - When I installed this it fired right up and ran like a top for about a half hour and then the tack dropped off and didn't come back. So I unplugged the dis, waited a few minutes and plugged it back in. After that it fired right up and the tach was working, I drove it around and it worked perfectly then I shut it down and now it's cranking and sputtering but not starting.


I'm stumped, the check engine light comes on when the tack drops out but I don't have an obd 1 reader, it has 40 pounds of fuel pressure and strong spark at the coil pack. It has a new harmonic balancer and bolt and ignition switch. It almost seems temp related, maybe a coolant temp sensor flooding it, but I don't know. The tach episodes seem so random. Any advice would be greatly appreciated.



Thank you.
 

DOUG H

SCCoA Member
There is supposed to be a heat transfering paste between the DIS & the mounting base. Since yours is new did you put anything on it before installing or was there still lots on the mounting base?It does sort of sound like a heat related issue though if tach drops & CEL comes on after running a while & then runs better after sitting.

Without scanning codes though, I wouldn't continue replacing anymore parts, until you have a better direction of whats going on with it. Good luck.
 

MaxR830

Registered User
There is supposed to be a heat transfering paste between the DIS & the mounting base. Since yours is new did you put anything on it before installing or was there still lots on the mounting base?It does sort of sound like a heat related issue though if tach drops & CEL comes on after running a while & then runs better after sitting.

Without scanning codes though, I wouldn't continue replacing anymore parts, until you have a better direction of whats going on with it. Good luck.
I scraped off the old paste and put automotive thermal paste stuff from my local autozone on. I'll invest in a code reader and get back to you with what I find. The tach usually dropped out when heating up. Would go off, after about 5 minutes of driving would come back and stay on.
 

MaxR830

Registered User
There is supposed to be a heat transfering paste between the DIS & the mounting base. Since yours is new did you put anything on it before installing or was there still lots on the mounting base?It does sort of sound like a heat related issue though if tach drops & CEL comes on after running a while & then runs better after sitting.

Without scanning codes though, I wouldn't continue replacing anymore parts, until you have a better direction of whats going on with
Hello all,

I'm new to the super coupe gang and just recently bought what is turning out to be a lemon 1991 thunderbird super coupe. It cranks and sputters like it's trying to go but won't start, it will also stop cranking and all lights will go out for a split second almost like cranking on a low battery but the battery is new and charged, then go right back to cranking. Here is what I've replaced. In this order.



Plugs

Idle air control valve

Coil pack

Fuel filter


Cam positioning sensor - When I replaced this it ran for about 3 minutes then died.

Crank position sensor - When I replaced this it ran perfectly for about a day then I noticed the tach would drop off and the check engine light would come on but the car would run fine. Then after a few minutes the tach would come back. Then I went to start it one morning it would crank and sputter but not start.


New DIS module - When I installed this it fired right up and ran like a top for about a half hour and then the tack dropped off and didn't come back. So I unplugged the dis, waited a few minutes and plugged it back in. After that it fired right up and the tach was working, I drove it around and it worked perfectly then I shut it down and now it's cranking and sputtering but not starting.


I'm stumped, the check engine light comes on when the tack drops out but I don't have an obd 1 reader, it has 40 pounds of fuel pressure and strong spark at the coil pack. It has a new harmonic balancer and bolt and ignition switch. It almost seems temp related, maybe a coolant temp sensor flooding it, but I don't know. The tach episodes seem so random. Any advice would be greatly appreciated.



Thank you.
Update: I unplugged the dis, let it sit for an hour and plugged it back in and it fires right up. This is not a solution though, just thought I'd add to the mystery.
 

sam jones

Registered User
Good afternoon

Check the condition of the DIS harness. Years of exposed wiring, and pulling/twisting at the connectors will cause intermittent signals to DIS/EEC.

Check the clearance between the DIS harness and the supercharger belt.

I used the EVTM to find a 1991 and 1992 DIS harness needing a rebuild. Both had similar issues as yours.


Failure points where the CAM, CRANK, the gray and black DIS and the COIL pack connectors.
 

35th

Registered User
Triple check your crank sensor as well just to make certing it's not hitting against the harmonic balancer when it's spinning they can be difficult to align
 

Falcon20x

SCCoA Member
" all lights will go out for a split second almost like cranking on a low battery but the battery is new and charged, then go right back to cranking. "

Located below the steering column, check your ignition starter switch. If you see a gap between the plastic and the metal, it might be your issue.
 

Falcon20x

SCCoA Member
here is what you do not want to see
 

MaxR830

Registered User
I ran the codes for both a running test and ignition test and here is what I got, there are a lot of them so I'm guessing some might be old stored in the system.

212 - Loss of ignition diagnostic monitor signal
214 - Cylinder identification circut failure
Cylinder 4
129 - Insufficient mass air flow change during dynamic response test
167 - Throttle position sensor fault during dynamic response test.
225 - Knock sensor fault during dynamic response test.
538 - Insignificant rpm change during KOER dynamic response test.

With the car actually running we drove it around because sitting at idle with no tach reading, the check engine light wouldn't come on unless you applied a bit of throttle.
Below is after driving it around.

118 - coolant temp sensor above maximum voltage/ 0 to -40 indicated.
157 - Mass airflow sensor fault. Low voltage.
158 - mass airflow sensor fault. High voltage.

Before posting this I tried to start it after sitting all night and in 30°F weather it fired right up and ran with a tach reading. I drove it around and everything worked once the motor got up to normal Temps I went and shut it off, now same thing as before really hard start.
 

DOUG H

SCCoA Member
The code 118 would explain the hard start when hot- thinks the coolant is below 0 F. So sensor or the wiring there likely.
Not sure on why it would have 157 & 158 at the same time, others here may though? It would explain why its turning light on though when accelerating. ECM sees request from TPS for more & a coresponding increase in r.p.m., but no increase in air flow from MAF.

None of those explain the drop in tach signal though & it stiil seems to be temp related so, new dis is bad or cam sensor or the associated wiring for them both.

I would ignore any of the codes in regards to dynamic test for now, as maybe the throttle blib wasn't done when requested? That would bring those 4 codes.
 

sam jones

Registered User
Good afternoon


157 - Mass airflow sensor fault. Low voltage.
158 - mass airflow sensor fault. High voltage.

The EEC has not received a MAF sensor readings. Power and signal are out of limits . Check the connector connector for damage, corrosion and or security. A voltage test might be in order. There are many youtube tutorials how to perform a ford 4 wire maf sensor voltage checks. This would be an excellent time to purchase year specific EVTM.

Example below.


 

MaxR830

Registered User
Update : I went ahead and ordered a new MAF because the connections on the DIS appear to be good, I also ordered a EVTM and plan on going through and checking all the grounds. I will be installing and testing everything at the end of the week and will update this forum with my findings.
 

Hiram1

Registered User
Bro none in this group are able to respond an accurate answer. Had an issue weeks ago i was asking for the images for the sc vacumm none of them gave me answer i had to get into this forum and find some pics that help me out. Im having a hard time with my 1992 tbird super coupe, mines wont start it had started 2 years ago now it wont. I have replaced the fuel pressure and some other things but i have remove the harness and double check it and there we go i had my harness really bad condition beeing twisted and old looks like the sun already afected the harness and had to rebuild it my self with tape and some black thing covering it also tape the parts where i can see the copper cable. ill be trying get it back on in few days send me whatsapp ill help you out. +52 6623876236
 

KMT

Registered User
...none in this group are able to respond an accurate answer. Had an issue weeks ago i was asking for the images for the sc vacumm none of them gave me answer
Bit harsh, I think. You were supplied plenty of answers/images of SCs that are stock, but as it turns out, your car isn't - burden is on you to take it from there, not strangers on the internet. When you own a hacked up car like yours with a non-factory brake setup, it should not come as a surprise when you can't get 'accurate' answers.

Next time, and now that you know, be sure to point out that you car has been changed since it left the factory so you can save time dangling in the wind.

And that harness repair...I hope you took pains to redo any missing/damaged shielding or you risk additional issues later.

Good luck.
 

KMT

Registered User
Update : I went ahead and ordered a new MAF because the connections on the DIS appear to be good, I also ordered a EVTM and plan on going through and checking all the grounds. I will be installing and testing everything at the end of the week and will update this forum with my findings.

Did you try cleaning it first?

The tach episodes seem so random.

My 35th had the same issue when I first got it.

It's random when the ECU doesn't get valid signals and is forced to supply look-up values from default tables to make the engine run, then later the ECU will check for valid signals sometime during the drive cycle, and if they are still missing, all heck breaks loose. Did you know you can use the Maintenance monitor as a debug tach? It's on the same circuit.

Took a new cam sensor, fresh front harness, new body/engine ground strap (along with connection cleaning at it's bolt on the body on the pass side) from the motor mount, before it behaved. All that and access to an EVTM, of course.

Good luck.

Ken
 

KMT

Registered User
Missed the edit window...again ;)

Those MAF readings may simply be the result if an incomplete/incorrect code read. I think your symptoms point elsewhere.

The tach episodes seem so random.
The tach usually dropped out when heating up. Would go off, after about 5 minutes of driving would come back and stay on.

Dancing tach when warming up is most likely co-incidental. Again, the engine is just doing a drive cycle test. Root cause(s) are always there, they just surface when the ECU decides to look under the bed.
 

MaxR830

Registered User
I'm not sure if anyone will read this update but my Super Coupe is back and running! I put a new ECU in and still nothing so I trailered it to a shop and within the day they had fixed the problem. I don't have the exact list on me but the main no start issue was.... The O2 sensors. One was shorted and the other was something like a thousand mA over voltage. From how they explained it the car would try to start in open loop but the shorted sensor would force it into closed loop where it would read the other O2 sensor being off, the car would pour fuel to itself and flood out on startup. That's why when left for a while the cylinders would dry out and it would start. They also explained the metal portion of the cam sensor, the plate that actually gets read is adjustable and was off causing long crank times which only made the problem worse. I hope this helps anyone who is having the same issues and appreciate everyone's support!
 

TBirdSC89

SCCoA Member
I think this is the issue with my SC, I'm going to replace my o2 sensors (not sure if they've ever been replaced) and see if it'll run. I got the same maf sensor faults also
 
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