Custom Dodge Magnum Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
159 Posts
Discussion Starter · #1 ·
So a couple of days ago I ran through a car wash in the morning. Been a while so I paid for the under body wash. I drove it about 1/2 mile or so to get the moisture off. When I left work (5 degrees outside) the engine started fine but was very loud. Sounds like an open exhaust and it seemed to be hesitating. I pulled off to a parking lot and got out to look underneath the car. Nothing out of the ordinary and (get this) it sounds fine idling. Hop back in the car and it is loud.

So I thought there may be some moisture that got somewhere and it just needed to get burned off. Sure enough when it warmed up it stopped sounding bad. Next morning (yesterday) it sounded bad again. It seemed to still be hesitating. After a mile or two the hesitating is gone but it seems to have less power / throttle response.

Last night I got the front on ramps and went to have dinner. So she sat about 1 hour. I had my wife start the car while I was under and looked at the exhaust. I didn't see any leaks and again it sounded fine from under there and in the cabin. Must need to cool off more

I left the car on the ramps over night. I took off the engine tray to get a better look at the bottom of the engine. 15 deg outside. My wife started it and gave a bit of gas (2500rpm) a few times. Same thing as last morning. Sounds fine outside the car but loud inside. Still felt the hesitation on the way to work.

I have a inTune so I logged while my wife started the car and revved it and while on my way to work. Not sure what to look for in the log, though. I did notice that the "Actual Spark cyl 1" and "Base Spark" (deg) was all over the place. Actual was min:-2.5 to max:40.5 and Base was 8.5 to 41. Seems odd to me. I checked for codes with the inTune and it doesn't see any. Should I try the key dance?

I have been running regular gas (87oct) for about 5 fill ups with the base inTune 89 tune. Never had anything like this. Can't see how a car wash could cause this other than some sensor quit. O2 maybe? The engine cover was installed then so the engine itself would not have gotten spayed. Would pulling fuse 11 to reset the adaptives help? Any ideas would be great. Thanks.

2008 3.5L V6 SXT with 4 speed BTW.
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #2 ·
I went out and tried the key dance (with mileage showing, 3 Acc to run (dont start) back to Acc quickly) and have no codes. Figured I'd start it and sure enough it still is loud and hesitating. I revved it twice and it was not a smooth up and down. It acted like it was missing a few fires. Even worse on the second rev as it stopped climbing rpm for 1/4 sec. Any ideas? Thanks.
 

·
Registered
Joined
·
1,593 Posts
My old taurus had a similar symptom and it was a cracked gasket seal between the manifold and the cat. Would be WAY louder in the car than outside and I am guessing a resonating sort of deal. As for the hesitation I would only advise going back to factory tune and 89 octane and see if that has any effect.
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #4 ·
So I did some searching here on 02 sensors and found a post that was similar to el guapo's from Fireman on flashing back to stock. Before I left work yesterday I flashed back to stock. She still felt hesitant but was not rough and loud like before. I drove it at lunch and thought it was still warm enough to cover the problem. Drove home fine (not as peppy without the tune).

So this morning at -7 degrees I drove the car up on ramps to crawl under and wiggle the 02 sensor connections. Sounded ok. Under the car everything looked ok and I could not get the connections apart. Not enough light and too cold fingers is my excuse and I'm sticking to it. Anyway, driving in today the car was fine. I still have a tank of 87 octane to use up. I'll switch back to the 89 tune after I get some higher octane gas in her.

I am guessing that it was the 87 oct and 89 tune got the engine adaptives out of wack. Thanks for the help el guapo.
 

·
Registered
Joined
·
104 Posts
Maybe put a can of octane booster in the tank until the 87 is gone!
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #6 ·
I have not had any more problems since flashing it back to stock. Late last week I put the Diablo tune back in and I am running fine with 93 octane gas. Calling this case closed. Thanks for the help.
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #7 ·
Well it seems I need to reopen this issue. This noise (loud inside, quiet outside, hesitation until it warms up) is happening again. I removed my tune and it still happens under 20 degrees F. If I plug in the car (oil heater) I don't have the issue. Any more ideas on what to look at?
 

·
Registered
Joined
·
159 Posts
Discussion Starter · #8 ·
Found something on lxfourms that is exactly like my problem. Seems a transmission mount can hold water. Replacing it resolves the issue. Going to try to get this part.
Odd, loud, cold start rumble and vibration. - Page 2

At the end of the thread there is a post from a guy in Canada that has been dealing with this for 3 years!
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top