car running sluggish, help.

[markus]

let me preface this by saying i'm a newb to vipers and have only had the car for about a month and a half, so please bear with me and forgive my ignorance. i have a bone stock 04 with around 17xxx on the clock. i noticed today that it's running extremely sluggish-as in at WOT it was accelerating slower than a honda civic. not throwing any codes, no smoke or smells of any kind. i know, i know, i should be doing my own oil changes, but i don't have jacks low enough to get under her yet. in the interim, i took it to what i thought was a reputable dealer, mistake #1. mistake #2: i never read the service sheet before i drove the car an hour and a half back to my house (i live in BF nowhere). service sheet says they gave me 9qt of 5w40, and i know the manual says i need 10qt of 10w30. i get home, check the oil, dipstick reads fine after a check and a re-check. when i first noticed it, i pulled over, turned it off, let it sit for about a minute in case it had a brain fart, restarted, same effect. what could the culprit be?
thanks in advance

 

[ViperGeorge]

Plugged Cat?? Bad Throttle Position Sensor???

 

[Martin]

The oil should be fine - in fact, if they put 5w-40 in it, you probably got Mobil 1 diesel truck oil, which in my opinion is a heck of a lot better than the standard 10w-30.

Now, regarding the performance issues. Are you only experiencing the issue at WOT? What if you do a few run-ups with various gas pedal positions? Does the car start to choke at any particular RPM, or is it purely throttle-position related?

If it runs fine up until you get to WOT, that knowledge should help to diagnose this. When you get to WOT, the car goes from closed-loop engine control to open-loop, and that affects things like fuel delivery.

Without knowing what's up and hearing the car myself, my guess would be that you've got plugged cats and the issue is happening when you get to a certain RPM and load rather than a throttle position. It's not all that uncommon, and some high-flow cats might be in your future

 

[markus]

i'm only experiencing it at WOT. you can hear the engine working hard as it normally would under WOT, just not getting the corresponding acceleration out of it.
also, it doesn't choke under any throttle positions and part-throttle it runs fine.

 

[Martin]

First check your Throttle Position Sensor - the car might not think it's at WOT even though it is. Also consider that your cats may indeed be plugged. All in all, those are pretty easy things to fix. With some diagnostic equipment, you can check the TPS functionality - or just bring it in to your dealer and he can check it to see if it's good or not. They're cheap, so if you want to just swap it out, that's an easy thing to do. The cats probably need to be changed out for performance reasons anyhow, so it couldn't hurt to take those on.

 

[markus]

thanks guys, i've made a checklist:
replace cats (throwing in a cat-back as well since i'll already have all that apart)
check tps
check plugs, fuel/filter (thanks to a member via pm)

 

[markus]

so i was thinking, if it was a clogged cat, wouldn't it then run red hot even after a mile or two? wouldn't there also be restricted flow coming out of the exhaust? i drove up the street and back, cat's don't appear to be hotter than usual, but it did take me 9 seconds to go from 0-40 lol

 

[ViperTony]

Maybe it's pig rich at WOT. Has it been on a dyno and if so what does the air-fuel ratio look like? Was this ocurring before the oil change or did it start after the oil change? Did the dealer do anything to the PCM? Any SCT tunes recently installed?

 

[markus]

it's never been on a dyno, has factory tune. ran fine for the 1.5 hour drive home from the oil change. it was the time that i drove it after that that this started happening. not noticing a gas smell, but i'm definitely not going to rule out a/f. maybe the pcm is pulling every last ounce of timing for some reason? i'm starting to think this is a pcm or pcm related issue. i have a 1.5 hour drive to the viper tech in richmond on thursday, i just want to be sure this thing won't burn to the ground en route.

 

[Martin]

so i was thinking, if it was a clogged cat, wouldn't it then run red hot even after a mile or two? wouldn't there also be restricted flow coming out of the exhaust? i drove up the street and back, cat's don't appear to be hotter than usual, but it did take me 9 seconds to go from 0-40 lol

Generally, if it's clogged, it's because it isn't able to burn off the hydrocarbons anymore. So, it just keeps getting more and more clogged. If it isn't burning off the gunk, it isn't getting hot - so you have little to worry about in that regard.

 

[markus]

Generally, if it's clogged, it's because it isn't able to burn off the hydrocarbons anymore. So, it just keeps getting more and more clogged. If it isn't burning off the gunk, it isn't getting hot - so you have little to worry about in that regard.

that's good to know, thank you. so if that is the case, it would just get worse and worse? as in the worse it gets, the worse it gets?

 

[Martin]

If the problem is indeed with the cats, yes - it won't get any better. It's also not a good idea to drive it with what amounts to a potato stuck in the tailpipe. That pushes the car way outside of its fuel mapping, and all you're doing is dumping fuel into the cylinders that can't burn. But, you were saying that the problems only manifest themselves when you're at WOT, so you should be OK for a drive to the dealer.

 

[plumcrazy]

sounds like cats to me and if it is, do not go WOT.

 

[markus]

that's good to know. knock on wood that i make it there, they diagnose it quickly and it's something as simple quick and cheap as a cat replacement.

 

[hdscreens]

Give us a detailed update when you get issue resolved.

 

[kblake905]

My car had a similar problem, it would not turn more than 3000 RPM without coughing and backfiring, it was a plugged cat! As a quick test you could pull the spark plug wires on one bank, if you pick the bank without the plugged cat it will run worse or not at all.
Good luck

 

[Venomiss]

Interested to see if you are under warranty and what the problem is.

 

[RTTTTed]

You could buy a cheapo oil pressure guage and plumb that into the Schraider Valve on the Intake manifold. (It has a valve cover cap and once that is removed you'll see what looks like a tire valve stem. remove that and attach the oil pressure line to the guage. Tape the guage to your windshield so you can watch the fuel pressure at WOT.

Pressure should be 55psi and 50psi @ WOT. If you were running rich there should be smoke. Also, remove several spark plugs and check the colors. WhiteishIvory is GOOD and dk brown or black is rich. WHITE with pieces of insulator or 'bits' melted out of the electrodes would be lean and seem to require a Compression test.

Ted

Ted

 

[slysnake]

Could it be something simpler? Did you disconect the battery at any time? Perhaps the PCM just needs to re-learn the throttle positions. Keep in mind I know nothing. But I seem to remember reading something about this before.

 

[markus]

car is currently not under warranty. having it looked at tomorrow by a local guy to see if he can diagnose it and if not monday off to the viper tech.

You could buy a cheapo oil pressure guage and plumb that into the Schraider Valve on the Intake manifold. (It has a valve cover cap and once that is removed you'll see what looks like a tire valve stem. remove that and attach the oil pressure line to the guage. Tape the guage to your windshield so you can watch the fuel pressure at WOT.

Pressure should be 55psi and 50psi @ WOT. If you were running rich there should be smoke. Also, remove several spark plugs and check the colors. WhiteishIvory is GOOD and dk brown or black is rich. WHITE with pieces of insulator or 'bits' melted out of the electrodes would be lean and seem to require a Compression test.

Ted

Ted

thanks ted, i'll pull the plugs and check them. that valve you speak of, mine has no cover. could there be any freak possibility of that freaking the system out?

Could it be something simpler? Did you disconect the battery at any time? Perhaps the PCM just needs to re-learn the throttle positions. Keep in mind I know nothing. But I seem to remember reading something about this before.

i myself am new to this and also had the notion it could be a pcm thing. ill try and do a hard reset of the pcm. any specific fuses anyone knows of to pull?

 

[RTTTTed]

No, the cover missing will not make any difference, but you should have a metal cap over it so that nothing accidently hits the valve spraying high pressure gas and fumes all over the place.

I'm guessing an ECU problem, but the more tests that you do,eliminating problems, the more money you save instead of the mechanic doing the same thing while you pau him $50-135 per hour.

Ted

 

[VIPER R]

How about a bad sensor putting the car into limp-mode?

 

[RTTTTed]

How about a bad sensor putting the car into limp-mode?

The ECU would detect a bad input and give a CEL/code.

I suspect a bad ECU but if you don't have an extra and can't borrow one from someone else ...

I have an extra ECU AND and extra Viper

 

[markus]

lol thanks for all your input ted! too bad you're all the way up in BC!!

 

[RTTTTed]

lol thanks for all your input ted! too bad you're all the way up in BC!!

Your location says "Wherever I lay my head" so I guess I can't comment on your place, but if I lived too close to a racetrack I know what I would be doing for a living (working with my buddies Sean Roe and Larry Macedo).

As far as "All the way up in BC" I've been throughout much of the states because "All the way" is an excellent excuse to drive my Viper there. Still looking for someone to pay me for eoing that, but I'll just do the cross country and cross continental drives until they do.

Ted

 

[markus]

UPDATE:
here are some vids i just took:
normal: [media]http://www.youtube.com/watch?v=PlquhP-4nXI[/media]
drivers side injectors disconnected: [media]http://www.youtube.com/watch?v=Vdj2LfRb6NQ[/media]
passenger side disconnected (warning, graphic): [media]http://www.youtube.com/watch?v=Jut2sDwoqTc[/media]
anybody? bueller? bueller?

 

[Martin]

Plugged cat

 

[markus]

what would explain the white smoke?

 

[plumcrazy]

when do you see the white smoke ?

startup ? idle? WOT ?

 

[markus]

wot. you can see it in the 3rd video if you look closely, i never noticed it until we popped the hood