Problem with my GTS (feels like she missing spark/fuel)

[Drummerboy]

Well guys, I bought a fresh new red top, new plug wires, a fuel pressure test kit and some other misc items and was on my way to try and troubleshoot the issue when she died on the highway on me, again. Had it towed to the dealer, again.

I'm going to instruct the Viper Tech to install the new battery, plug wires, a new Cam sensor and tell him about all the other ideas in this thread (Injectors, loose ground/wires, etc) and have him drive the piss out of it with a datalogger and troubleshoot it from there if need be.

Will report back when I get word from the Tech..

- Rob

 

[dave6666]

Well guys, I bought a fresh new red top...

Optima? How old was the previous one?

 

[Dom426h]

hmmmm Drummer, you might not have the same issue as me. Mine has Never Died. I can always either ride untill it clears up, or if its bad enough i'll pull over and shut her down and wait a few min befor starting back up fine. However, my problem has apparently been getting worse recently. I decided to leave her parked this whole week untill i get all my parts in.

 

[Sweet Ride]

hmmm, on second thought i think i might just be getting my hopes up. With that notch on the camshaft spinning very fast & close to the sensor i'd think it would be pretty difficult for anything to accumulate on it. Then again i have no idea just how magnetic it is when On...

I know I'm late to the party but I say it's probably not the cam sensor. Cam sensors go bad in my fleet trucks more often than I would expect and it can happen. Usually if a cam sensor goes bad the vehicle will die or run/idle crappy at certain RPM's. You may not get a CEL with a bad cam sensor.

You may want to pull the harnesses from the PCM and check for moisture in the harness or on the PCM terminals.

Lastly, according to "The Book": "...The PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines intake manifold pressure relative to atmospheric pressure. Also, atmospheric pressure is updated at WOT. Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and A/F mixture."

Check/replace your MAP sensor and see what happens.

 

[Drummerboy]

Dave: I don't know how old the battery is, Didn't have the opportunity to check, but I figured I'd get a new one just to eliminate the variable.

Dom: My issue began exactly as yours - it began with the light intermittent hesitation that would clear up and then run fine for days and then ultimately worsened to the point where I would stop and wait and start her up, then to the point where it would eventually die. Interesting that when I got it back from the tech (after installing the New crank sensor) I experience the same exact sequence, only it was accelerated greatly. The first day I got it back, it was minor hesitation. By the second day it was breaking up, and by the 3rd day it was breaking up and dying. Previously, the issue took weeks to progress.

The Tech told me today he suspects it could be the PCM which he mentioned is usually warrantied for 8 years, but it may not be covered for me since I had an SCT performance tune on it. *****!

- Rob

 

[Dom426h]

Hey! everyone can join this sick party

Thanks for the tip, if i can catch up with another viper before my parts come in thur/fri then i will try swapping our MAP's to see if any differance

Already checked my PCM connections along with Every other conneciton i could get my hands on.

 

[Dom426h]

Yea, when i sensed my prob getting worse i said F it, Parked her, and called chuck(who is puzzled by the way) and ordered some parts

Why didnt you unload the SCT Tune before going to the dealership. DUUUUUUH!

 

[Dom426h]

The Tech told me today he suspects it could be the PCM which he mentioned is usually warrantied for 8 years, but it may not be covered for me since I had an SCT performance tune on it. *****!

Call chuck and ask him how many PCM's he has ever had to replace. Im curious. Aah nevermind, i'll ask him and report back tommorrow..

 

[Drummerboy]

Let me know!

It is back on the stock tune now - but he told me the units keeps super detailed logs of everything that's done to it - to the point where he said it logs what pages were viewed by him with his scan tool & software. I was surprised to hear that!

- Rob

Call chuck and ask him how many PCM's he has ever had to replace. Im curious. Aah nevermind, i'll ask him and report back tommorrow..

 

[dave6666]

Lastly, according to "The Book": "...The PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines intake manifold pressure relative to atmospheric pressure. Also, atmospheric pressure is updated at WOT. Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and A/F mixture."

Check/replace your MAP sensor and see what happens.

Could a vacuum leak cause the problem at the MAP? Or assuming that a vacuum leak is not intermittent, the problem would be constant? Which therefore doesn't really apply here.


On a related note, if only that super detailed PCM log could play back video of everything that Chad has done to a waitress in his car. Priceless...

 

[Dom426h]

Drummer, the Wiz says he has only replaced ONE or maybe 2 PCM/ECU's(same ting) on a Gen2 EVER. Also said typically a bad ECU would be like a light switch. aka not intermittent.

Also, sometimes ECU's will develop a memory issue which is why he recommends grounding the positive cable to do a full memory dump reseting the computer.

-----------------------------------------------
Dave, I have jiggled all the vacuum lines while the car has been running several times with no result.
I Wish it was something that simple

 

[Drummerboy]

Appreciate the info Dom, and it makes sense. I'll check to see if there are any differences between the Gen-2/3 PCM's as I have an SRT, but the PCM is def on the bottom of my worry list for right now.

Will be nice when we figure this one out, huh!?

- Rob

Drummer, the Wiz says he has only replaced ONE or maybe 2 PCM/ECU's(same ting) on a Gen2 EVER. Also said typically a bad ECU would be like a light switch. aka not intermittent.

Also, sometimes ECU's will develop a memory issue which is why he recommends grounding the positive cable to do a full memory dump reseting the computer.

-----------------------------------------------
Dave, I have jiggled all the vacuum lines while the car has been running several times with no result.
I Wish it was something that simple

 

[Sweet Ride]

Could a vacuum leak cause the problem at the MAP? Or assuming that a vacuum leak is not intermittent, the problem would be constant? Which therefore doesn't really apply here.

Since the MAP has a pressure diaphragm in it and is also an electrical sensor, it is very possible that it is an intermittent fault. It may not be directly caused by a vacuum issue as the pressure diaphragm itself may be internally damaged or worn out. If it is not providing a proper resistance reading, it would be sending a false signal to the PCM possibly causing a drivability issue.

 

[paulsgts]

I had a similar problem with my 97 GTS it ended up being the ignition wires. Have the car running and spray the wires with a spray bottle and see if the idle changes look and listen for the wires shorting out. I was at the beach and this happened to me. I went to a gas station and pick up some black electrical tape. I taped up the 2 bad wires made it home with no problems. Obviously I ordered some new wires and replaced them. It doesn't matter how old the wires are if they rubbed on the manifold they will melt and short out. They will also cause a intermittent problem like you have. Also if your car is missing the raw fuel can damage and over heat the cats.

Hope this helps
Paul

 

[99 R/T 10]

If it is the PCM and since you have some minor mods, would getting a Mopar PCM help not only the problem, but to add more power?

 

[Dom426h]

Not the wires. again: Wish it was that simple

Dont think the problem is the PCM. also, the performance(or lack there of) from the MoparPerformance PCM is debatable. Also i have an SCT awaiting to dyno tune the GTS once she is well

 

[dave6666]

Appears we are on the same page about the MAP sensor...

On the other hand which sensors have moving parts? Things that can go kinda bad, sometimes bad, but not always bad?

Cam and crank sensors - Probably hall effect and no moving sliding parts.

IAT - Thermistor? No moving parts if so.

MAP sensor - Diaphragm to stress cell or other resistive device? Maybe moving parts.

TPS sensor - Sliding resistive device.

IAC - Moving parts... Yup.

Coolant thermostat - Thermistors

How about a faulty injector or injector connection? Or would that throw a code for sure?

Since the MAP has a pressure diaphragm in it and is also an electrical sensor, it is very possible that it is an intermittent fault. It may not be directly caused by a vacuum issue as the pressure diaphragm itself may be internally damaged or worn out. If it is not providing a proper resistance reading, it would be sending a false signal to the PCM possibly causing a drivability issue.

 

[Sweet Ride]

Appears we are on the same page about the MAP sensor...

Well said and good call!!!

 

[Dom426h]

Drummer, whats your status?
Im working on the CAMposition & o2 sensors. Maybe i'll have some results by the end of the day.

damn this CPS is a Beeeotch...

 

[dave6666]

What does the face of the old sensor look like?

 

[Sweet Ride]

What does the face of the old sensor look like?

My guess is this:

or this if it's dead:

or this if it's an intermittent fault:

or this if it's not the cam sensor: :*****:

 

[Drummerboy]

Hey Dom,

Current status: Missing out on great weather and awesome drives while my ride sits in Limbo at the dealership.

I left instructions for them to replace the plugs, plug wires, Cam Sensor (as I mentioned, Crank has already been replaced)and a new battery. I spoke with the tech and told him to check for loose grounds, connections, fuel pressure, the works. He said he would drive around with a scan tool until the problem arose so he could browse the logs. I feel I should have specifically mentioned a few things from this post like Map and O2 sensors, or even just showed him the link to this thread, but I would assume that being an experienced Tech, he would know to check these out..

I'm thinking I should have tried to do the work/troubleshooting myself now, instead of having it towed back to the dealership. I'd love to get down and dirty with things, I just don't have much mechanical experience and don't feel super confident diving in and risking burning myself, the car and the house down in a bloody fireball.

- Rob

Drummer, whats your status?
Im working on the CAMposition & o2 sensors. Maybe i'll have some results by the end of the day.

damn this CPS is a Beeeotch...

 

[Tom F&L GoR]

If he drives around with the really good scan tool he will find it. I borrowed one once and discovered both 02 sensors were bad. I was surprised because my CEL did not illuminate. it turns out that if the O2 sensors do not have their "problem" for more than 4-8 seconds at a time (it was some surprisingly long time period) they did not exceed the minimum time to light the CEL.

I am not saying it is the O2 sensor, just that the dealer version of a scan tool will "see" much more. Good luck.

 

[kevin96rt]

I have to agree when I had the same exact problem all my research pointed to these same items.My problem did turn out to be a loose connection at tps.Only way I found it was wiggling all connections while car was idling.
Goodluck I feel your pain

On the other hand which sensors have moving parts? Things that can go kinda bad, sometimes bad, but not always bad?

Cam and crank sensors - Probably hall effect and no moving sliding parts.

IAT - Thermistor? No moving parts if so.

MAP sensor - Diaphragm to stress cell or other resistive device? Maybe moving parts.

TPS sensor - Sliding resistive device.

IAC - Moving parts... Yup.

Coolant thermostat - Thermistors

How about a faulty injector or injector connection? Or would that throw a code for sure?

 

[Kiaser]

Does this sound like the same problem:

While cruising along, the throttle sometimes just completely stops working. The rpms start to drop slowly, and I can pump the throttle in and out with no response. After anywhere from a couple of seconds to sometimes up to 10 seconds or longer, the throttle will respond just like normal. This used to happen only once every few outings, but over a year it's progressed into a nearly once every 15 minute thing.

If so, add a 1994 RT/10 to the list and I'll start reporting my findings.

 

[Rock Morgan]

DOM,

My battery change did not solve my problem either. It came back with a vengence today. It started about 60 miles into my trip and ended up with a wreck. I was driving about 55 mph in the rain (pop up shower) taking it easy at low rpm in 5th so I would not hydroplane, and it started surging. The rear tires broke traction, the car spun out across two lanes of traffic, and into the median I went. Now I have a bent rim, need a new bumper cover, and have to figure out what's wrong with the engine too. It was by the grace of God I didn't hit anyone or total the car. I'm going to go change my huggies now. I hope we get this thing figured out soon. I have pictures on my Iphone I'll post as soon as I figure out how to.

 

[dave6666]

DOM,

My battery change did not solve my problem either. It came back with a vengence today. It started about 60 miles into my trip and ended up with a wreck. I was driving about 55 mph in the rain (pop up shower) taking it easy at low rpm in 5th so I would not hydroplane, and it started surging. The rear tires broke traction, the car spun out across two lanes of traffic, and into the median I went. Now I have a bent rim, need a new bumper cover, and have to figure out what's wrong with the engine too. It was by the grace of God I didn't hit anyone or total the car. I'm going to go change my huggies now. I hope we get this thing figured out soon. I have pictures on my Iphone I'll post as soon as I figure out how to.

Man that really *****! A related comment to your fender bender... be sure and take a look at the suspension control arms where they mount to the chassis - the pivot points. There have been some failures, and an impact big enough to bend a wheel could start a crack maybe.

 

[Rock Morgan]

Man that really *****! A related comment to your fender bender... be sure and take a look at the suspension control arms where they mount to the chassis - the pivot points. There have been some failures, and an impact big enough to bend a wheel could start a crack maybe.

Dave I'll do that, and check all the other pivot points too. The car just freaked out doing 55mph. If the folks behind me had not stopped to check on me and told me what happend, I would have bet money someone hit me from behind. He was about to pass me on the left and he said the car just took a hard left and there was nothing I could do. This thing is going to be gone over with a fine tooth comb before it gets back on the road. Had I not been going slow I would have gone through the median into on-comming traffic and I'd be toast.

 

[Daddy Long Stroke]

Wow..Wish had I seen this thread earlier.

I would bet money that your problem is one of your 02 sensors, front right or front left. Had the exact same problem. Very intermittant issues. Not sure if you have pulled the codes, and how many times, but mine only showed up the very first time I pulled them. Once I erased it, it never came back. I chased a coil pack, battrery, ect. problems also.

02 sensor......... Blam....Problem fixed.

 

[cornfish]

Hey Guys,

I have a similar issue as well. What I am noticing is when I first start up the car, it idles fine and sounds fine but when I start to drive, it feels like I have lost a boat load of power for a very short period of time. If I punch it, it eventually will recover and the car launches forward (haha.) It drives fine after that although occasionally, when I stop at a stop sign or light, it idles really low and rough and blipping the throttle seems to recover it. I honestly have been having this issue for about a year now and CAN'T FIGURE IT OUT! ******* me off actually.

Here are the things that I have replaced/done recently -
- Replaced my battery
- Replaced the map sensor
- Replaced the plugs
- Replaced the plug wires
- Replaced the fuel filter
- Replaced my fan shroud (not related)
- Replaced my radiator twice (pwr ***** so I got one from JonB, not related)
- Took it to a local shop twice to see if they could get it to happen (they didn't)

I have a 1998 gts with SVS cams, headers, exhaust, larger throttle bodies, high flow cats, etc. The car just rolled over 17k miles (got it with under 5k).

Should I just bite the bullet and get new O2 sensors? I seem to be on a roll for buying and putting in things I don't need (other than the radiator.)