Help!! 94 RT/10 wont stay running. Not alarm/pump/battery/fuses/relays

sirvelonodnarb

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Hey Everyone.

Bought my RT/10 Viper from Porsche Austin 2 weeks ago, and half of that time it's been stuck in the garage. I've spoke with the almighty Steve about bypassing the alarm as well as MANY other things. None of which worked. I'll list those things shortly.

Some background on some work done on the car about 140mi before this issue:

Compression/Leak down test
Fuel pressure confirmed and of no issue, though they didn't list what it was.
Fuel filter replaced
All fuel injectors removed/sonic cleaned/flow tested
Oil pan gasket replaced/oil change
Fuel tank filler to tank grommet replaced due to leaking
Power steering pressure line replaced
Plug wires were incorrectly routed by last owner
Ignition system tested with no faults found

With Steve, we noticed that one of the past owners disconnected from the Security box under the dash - and surprise - there was a second box plugged in? Looks like a wiring mess, but not too crazy.

There was also a rocker switch in the panel, but it only went to a ground. The other end was just dangling. We've checked some of the relays on the RH side of the engine bay, all associated fuses, we bypassed the alarm just for grins (key fob still works to disable), new battery. We checked for fuel pressure to the motor via the valve out back (need to get exact #'s).

The car acts EXACTLY the way the alarm shut off does. However, we've confirmed we dont have the dash lights nor is it active (both via fob and bypass).


Anyone willing to provide me some insight? Car is not flooded either, started it w/ full throttle to drain it. The car ran perfectly for the entire week prior. I shut the car down to get a drink and came back to these issues.

Thank you to everyone so so much. This car has been my dream since I was six and a week in it's testing me. lol.
 

Steve-Indy

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This is a tough one. Fuses good, unplugged 2nd SAM and replugged...same for RKE. As noted, fob still clears alarm set light. Manual SAM reset does nothing. Air filters OK, opening throttles slightly did nothing. Fuel squirts at Schrader valve on IM (early 94 with 4 stripe IM)...but pressure unknown at present.
No CEL noted.
He pulled and reinstalled ASD relay with no change. As I recall, still needs to swap starter relay with ASD as a test.

Sounds clearly like alarm shutdown, but with an obviously rewired system we have been unsuccessful with standard "tricks"...including new battery since interior lights had been found on and may have run original battery down.

Might be helpful to see if a DRB III with OBD I cable can give any useful info such as cam and crank sensor status.

This case needs help from a fresh viewpoint.
Any suggestions appreciated.
 
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sirvelonodnarb

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Steve - do you think it would hurt to plug back into original alarm system box and try the bypass?
 
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sirvelonodnarb

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update:

Swapped starter relay and ASD: Car started and ran like noted above.

Also, for grins, I plugged back into the original security alarm module, had the lights flickering and bypassed it w/ Steves recommendation. Went to start - same result as w/ the secondary SAM.


Id imagine that the fuel pump fuse (in the back of the car??) is fine being that the pump is priming?
 

Chad Spackman

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If the car does start, but won’t stay running, as is the subject of this post, throttle body’s not synced will do things like that. You can keep it going by applying throttle, but it’ll stall easily. Faulty MAP sensor will also do this. However based on all the talk of the alarm bypass I may have missed a full description of the symptom
 
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sirvelonodnarb

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If the car does start, but won’t stay running, as is the subject of this post, throttle body’s not synced will do things like that. You can keep it going by applying throttle, but it’ll stall easily. Faulty MAP sensor will also do this. However based on all the talk of the alarm bypass I may have missed a full description of the symptom

Thank you for the input. Re synced TB twice now. We unplugged vacuums so that we can bypass MAP. Ran better for a minute, but steadily dropped off.
 

Patrick

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A while back, my ‘97 GTS was hesitating on the road. After extensive testing, was the catalytic converter. Go figure!
 
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sirvelonodnarb

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A while back, my ‘97 GTS was hesitating on the road. After extensive testing, was the catalytic converter. Go figure!
I believe I have aftermarket cats.

We’re Going to put on an external fuel tank and pump to see if it is in fact the pump. Rather than taking the whole damn tank out w out being more than 95% sure
 

Chad Spackman

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Ok on throttle syncing. One comment, on my 94, the standard method (ie wide open throttle) will totally unsync them simply because the stop plates are unaligned. So I don’t use that method
 

Chad Spackman

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Sorry I missed this when it was posted. Re: resyncing TBs. I go through the WOT process and then look at the TBs with a foot able to press peddle. It’s pretty easy to see when the they lift off. On the one that lifts off FIRST, I lengthen that cable so that it lifts off exactly coincident with the lagging side. The manual states the side with the throttle position sensor,should lift off slightly before the other side. That’s nonsense IMHO. What it should state is that if you have any error, then error on the side with the tps lifting first. But ideally you want those butterflies to open at exactly the same time. Erroring with the non-tps lifting off first must not happen. This lets air in without the car’s ECU being aware of it. That causes all sorts of trouble at idle.
 

Viper Specialty

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I would suggest if you know anyone else with a Gen-1, swap the PCM's [both] and see if the problem goes away. many times when the PCMs are nearing a failure, they can often act just like that. If that is what is happening, you DO NOT want to keep trying as you risk further damage... and you want that thing unplugged before it melts down.

If the car acts fine on someone elses PCMs, send yours in to us for an overhaul.
 

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