Died while rolling

dumbstixlars

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Hey all, had an incident in my 03 and was hoping someone could shed some light. I finally got some replacement wheels and tires on my Cobra and took it out for a drive. It has been sitting for a couple of weeks and needed some heat in it (though it is 105 ambient here now).

Anyway, I had been driving for a bit (15 minutes or so) and was headed back home, in third gear, A/C on, and rolled into the throttle (60% or so at about 60mph). The car was making boost (10ish psi) and then it stumbled pretty hard. I lost power, but when I backed out of it and blipped the throttle I could hear the SC whine, at this point all the gauges except the boost gauge were dead, odo was all dashes, speedo and tach at 0. I made sure it was in neutral, flipped the ignition off and tried to restart it while I was rolling. From the sound of it, it seemed like the engine was struggling to start, but after a second or two of cranking, it fired up. It drove normal the last couple of miles home.

I know the alternators don't last long on these cars so I stuck my DMM on it as soon as I got home, but it was idling at 13.7 volts. Any ideas on what I could check or what it could be?
 

Steve Cea

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Did you blow any fuses ? This kinda happened to me once before , for some unknown reason I blew 2 fuses , my gauges we're all dead besides the boost gauge ( obviously it runs off of vacuum) found 2 blown fuses , replaced both never had the issue again knock on wood ?

Sent from my SM-G955U using the svtperformance.com mobile app
 

dumbstixlars

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Did you blow any fuses ? This kinda happened to me once before , for some unknown reason I blew 2 fuses , my gauges we're all dead besides the boost gauge ( obviously it runs off of vacuum) found 2 blown fuses , replaced both never had the issue again knock on wood ?

Sent from my SM-G955U using the svtperformance.com mobile app

Dunno about the fuses. The gauges started working fine after I cycled the key off and on.

Battery terminal tight? I'm assuming gauges and all worked fine once you restarted? Start with the obvious.

Yeah I wiggled the terminals when I got home and they were tight, also, when I power cycled the car everything went back to normal.
 

CobraBob

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This happened today? Have you taken it out for another drive? Is everything "normal" now?
 

dumbstixlars

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This happened today? Have you taken it out for another drive? Is everything "normal" now?

It seemed normal right after for the last couple of miles home. I didn't drive it anymore cause I have to prep one of my other cars for a race tomorrow, so I don't have time to mess with it anymore today.
 

01yellercobra

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Sounds like what my car goes through. I'd watch your alternator and battery. If it's hot out and I have the A/C going it'll act up. At least when I'm stuck in traffic. Once everything cools down, either by cruising with no A/C or parking it, everything works normally again.

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dumbstixlars

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Sounds like what my car goes through. I'd watch your alternator and battery. If it's hot out and I have the A/C going it'll act up. At least when I'm stuck in traffic. Once everything cools down, either by cruising with no A/C or parking it, everything works normally again.

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Well that is why I mentioned having the A/C on, I know everything under the hood had got to be roasting. I'll need to wait and save some money up. I'd like to get it on a dyno with an experienced tuner and see what it's doing with someone who knows more about these cars then I. It was dyno tuned by Murrillo a few years ago, I have all the paperwork. It lurched on me earlier in the drive when I got on it hard, but I just assumed that was the traction control kicking in since the tires are new and I was pushing it kinda hard. When it died on me I had the traction control off.
 

dumbstixlars

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The plot thickens. I decided to put my code reader on it despite the check engine light not being on. It is throwing a P0068 fault code:

P0068 FORD - Manifold Absolute Pressure/Mass Air Flow Sensor - Throttle Position Correlation

Read more: https://www.autocodes.com/p0068_ford.html

I notice when it is running the TPS is reading 17% at idle, engine off key on, fully floored it only reads 92%. The car has a Mafia on it, I am wondering if it is functioning correctly (I am not a fan of the Mafia).
 

MineralCobra

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Keep an eye on the alternator, when it gets hot under the bay especially with ac on the voltage could drop a good amount. My last alternator would fluctuate between 10v and 13.5 within minutes.. the regulators go nuts with the heat
 

T-bird88

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I had the same issue for a couple of years ago.
Dashes on the odometer means that there is no communication between ECU and instrument cluster.
It will take some time to establish the communication.
The engine was stumbling and sometimes die.

The ECU is grounded directly to the battery negative terminal via a splice connector.
The splice is located close to the battery, between battery and inner fender.
My problem was that I hadn't pushed in this connector fully.
I would first check this connector and make sure there is no corosion on the terminals.
 

dumbstixlars

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Keep an eye on the alternator, when it gets hot under the bay especially with ac on the voltage could drop a good amount. My last alternator would fluctuate between 10v and 13.5 within minutes.. the regulators go nuts with the heat

I had the same issue for a couple of years ago.
Dashes on the odometer means that there is no communication between ECU and instrument cluster.
It will take some time to establish the communication.
The engine was stumbling and sometimes die.

The ECU is grounded directly to the battery negative terminal via a splice connector.
The splice is located close to the battery, between battery and inner fender.
My problem was that I hadn't pushed in this connector fully.
I would first check this connector and make sure there is no corosion on the terminals.

Thanks for these tips, will investigate them on Sunday and update the thread.
 

bullitt2735

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I live in atx also, haven't found a tuner I like locally but I would highly suggest talking to vmp or have 04sleeper do a remote tune. VMP did my mail order tune and it is spot on, drivability has been great, they even fixed an issue of my car occasionally dying when coming to a stop. ( Ford had a tsb for this on early 03 models like mine) When I go tvs I'm going to switch to 04sleeper though as I have heard nothing but great things.
 

01yellercobra

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If you have a hand held and a laptop you can datalog it yourself. It's probably not the tune. If it was the time I'd think it would happen more consistently.

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dumbstixlars

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If you have a hand held and a laptop you can datalog it yourself. It's probably not the tune. If it was the time I'd think it would happen more consistently.

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The grounding issue that was brought up earlier makes a lot more sense to me honestly. I still would like to do an o/r X pipe and a GT500 MAF however. I have a laptop, I don't have the tuner unfortunately. The car was tuned by Murrillo motorsports back in about 09 or 2010 according to the receipts I got with the car. I don't know if anything else has been touched since then.
 

dumbstixlars

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Well I found the connector that T-bird was talking about, scraped a "little" bit of green out of it. Put contact grease in it, we'll see if it dies on me again. Going to take it out for a little drive in a bit.
 

Stage 4.6

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I have a similar issue with mine, but it only happens when the A/C is on, mine idles a bit low when A/C on and it occurs during city driving coming to a stop RPMs drop low and bounce up or just dies.
My tuner assured me he can correct the issue by adjusting some parameters in the tune.
He's a couple of hours away so i haven't took it back for adjustment, I know he can download the tune and email it too me but i dont trust myself messing with that hand held.
 

dumbstixlars

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Well I tried to drive the car down to a family member's house for Thanksgiving on Thursday. Didn't get halfway there and it died on me twice. Same symptoms, gauges went dead and all dashes on the odo. I turned around and drove it home, it was fine until I got it in front of my garage, it was sitting there idling while I was opening the door and then it died again, odo didn't turn into all dashes this time though.

Couple of things to note. There may not be enough battery in the car, previous owner put a (what looks to be) cheap Wal-Mart pop top battery in the car, if I don't charge it at least once a week it won't turn the car over. It also seems to crank the car slowly even after charging it for a few hours. I have a deep cycle yellow top on the way since this doesn't seem to be enough battery for the car.

Second, I am suspicious of the Viper Alarm on the car. This is mostly just because I am unfamiliar with them and I know how terrible most people are with installing electrical items in cars. PATS is supposed to be disabled on the car. It does this thing also where the theft light flashes for about two minutes after you start the car while it is running, is this normal if PATS has been turned off?

I need to finish a gauge install on another car of mine, but once I do that I am going to pull it into my shop and start chasing wires. Going to see if I can find the source of the parasitic draw on the car, it may be related to the dying, however unlikely.

ETA: I almost forgot, this has happened a few times as well. I will roll into the throttle, and the car will lose power for a split second. Hard enough that it will throw you forward and cause the seat belts to lock. Almost like it is cutting ignition, it did this to me once on my return trip home. I don't *think* it is the TC, it feels too violent. Plus I am pretty sure it has done this to me with the TC disabled also.
 
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hotcobra03

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I had issue like this..

was ground wire going from battery to radiator support..

wire burned inside where you can' see it..

for testing you can run a jumper wire..
 

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