Feels like running over a series of road reflectors.

[Scrippy]

Hey everyone,


Looking for opinions/ideas with a recent issue I've noticed. A little background…..Just replaced both EGR valves as well as the y-hose. While there I did spark plugs. No more bank 1 secondary air errors. It's been over 600 miles & 2 weeks since this work.This morning I went for a drive and when giving it full throttle in 1st & second there is a period around 2k to 3k in both gears where it feels like the car is running over a series of closely spaced road reflectors like those on a solid white or yellow line. 3rd gear and up do not produce this if on hard throttle. No errors, no loss of power, no weird shifts. It will happen in any drive mode S2-S5. I can't tell if it's a tranny, drive shaft or rear end vibration unfortunately. Any ideas, thoughts or experiences is what I am seeking.

[Etansinsta]

can you post a clip of the sound? you might not be able to hear the sound above 2nd gear due to wind noise

[DrFerry]

Originally Posted by Scrippy

Hey everyone,


Looking for opinions/ideas with a recent issue I've noticed. A little background…..Just replaced both EGR valves as well as the y-hose. While there I did spark plugs. No more bank 1 secondary air errors. It's been over 600 miles & 2 weeks since this work.This morning I went for a drive and when giving it full throttle in 1st & second there is a period around 2k to 3k in both gears where it feels like the car is running over a series of closely spaced road reflectors like those on a solid white or yellow line. 3rd gear and up do not produce this if on hard throttle. No errors, no loss of power, no weird shifts. It will happen in any drive mode S2-S5. I can't tell if it's a tranny, drive shaft or rear end vibration unfortunately. Any ideas, thoughts or experiences is what I am seeking.

Does it still happen when traction control is turned OFF?

[Scrippy]

Originally Posted by Etansinsta

can you post a clip of the sound? you might not be able to hear the sound above 2nd gear due to wind noise

I tried but there isn't enough audible noise to hear over the motor. It's definitely felt though. Besides road reflectors spaced out like 6" from each other it reminds me of the traction control kicking in kinda.

[Scrippy]

Originally Posted by DrFerry

Does it still happen when traction control is turned OFF?

Yes it does. On or off the feeling/mild noise is there. 1st & 2nd gears produce the noise. Inspected the under side of the car and nothing looks worn or shows rubbing. No leaks from rear end and CV boots look new still. I'm really hoping it's not the rear end dying!

[DrFerry]

Originally Posted by Scrippy

Yes it does. On or off the feeling/mild noise is there. 1st & 2nd gears produce the noise. Inspected the under side of the car and nothing looks worn or shows rubbing. No leaks from rear end and CV boots look new still. I'm really hoping it's not the rear end dying!

Sounds like a misfire under high load. Could be a failing coil pack, injector or even a bad plug. Check for misfire codes. Failing that perhaps it's a failing engine mount or transmission mount exacerbated by WOT high load acceleration in lower gears. Just some suggestions.

[Richbot]

what did you have to take apart to do the job you just did? That's where I'd start

[Scrippy]

Originally Posted by Richbot

what did you have to take apart to do the job you just did? That's where I'd start

Everything is assembled correctly. I was very meticulous with every part. I have no error codes present in the car. To do the EGR valves it's the removal of the plenum, rear engine hook, half the wiring harness (drivers side) and the vacuum pump. I replaced both valves, gaskets, securing nuts, heat shied bolts and the Y-hose. Also did the spark plugs and I torqued them to spec. I took pictures of things at each step to ensure everything went back correctly the first time. I've done the plugs 5 times now and I've never had an issue with ignition afterwards.

[Scrippy]

Originally Posted by DrFerry

Sounds like a misfire under high load. Could be a failing coil pack, injector or even a bad plug. Check for misfire codes. Failing that perhaps it's a failing engine mount or transmission mount exacerbated by WOT high load acceleration in lower gears. Just some suggestions.

No error codes. I use INPA & ISTA. I did motor mounts a year and a half ago. Could a coil pack produce a vibration like this without kicking out an error?

[DrFerry]

Originally Posted by Scrippy

No error codes. I use INPA & ISTA. I did motor mounts a year and a half ago. Could a coil pack produce a vibration like this without kicking out an error?

The car has a soft rev limiter which is a fuel cut when redline is hit. Since the rev limiter can feel like you described, I'm thinking a failing coil might also feel like a hard style rev limiter where ignition is cut. Cars with hard cut style rev limiters can feel violent so car makers use softer fuel cuts nowadays. People used to describe it as "bumping up against the limiter" and oddly enough you also describe the vibration as being like small bumps. Perhaps the rev limiter is being activated or as mentioned earlier a bad injector, coil pack or plug. Spark knock?

[Scrippy]

So it's not violent but it's noticeable. I feel like all the potential causes you mention would draw an error from the DME. I'm going to try and inspect my motor mounts this weekend. I looked under the car again and there are no fluid leaks from diff or trans nor signs of wear. Because it's only between 2&3k in 1st and 2nd only I think it may be worn mounts but I'm going to plug in and keep reading for errors. Thanks for all the ideas man. When I get it figured out I'll report back here.

[Richbot]

Broken wires and ground issues don't always throw codes. You'll have handled a bunch of harness that is at minimum 10 years old and been heat cycled thousands of times. That's what I mean by starting there. The ignition cables are designed for handling as part of the service procedure...some of them are definitely not and don't have a ton of tolerance for twisting bending and such.

All that being said, yeah I'd get some known good coils on there. They don't last forever

[Scrippy]

Originally Posted by Richbot

Broken wires and ground issues don't always throw codes. You'll have handled a bunch of harness that is at minimum 10 years old and been heat cycled thousands of times. That's what I mean by starting there. The ignition cables are designed for handling as part of the service procedure...some of them are definitely not and don't have a ton of tolerance for twisting bending and such.

All that being said, yeah I'd get some known good coils on there. They don't last forever

Originally Posted by Richbot

Broken wires and ground issues don't always throw codes. You'll have handled a bunch of harness that is at minimum 10 years old and been heat cycled thousands of times. That's what I mean by starting there. The ignition cables are designed for handling as part of the service procedure...some of them are definitely not and don't have a ton of tolerance for twisting bending and such.

All that being said, yeah I'd get some known good coils on there. They don't last forever

None of my engine/trans braided lines are disconnected or green from oxidation. I'm a Cali resident so things don't wear/oxidize or moisture out as much here. Wouldn't a coil out of tolerance always throw a code? My confusion is no errors but the turbulence/vibration on hard acceleration. No tunes and nothing coded out, 100% stock. Totally appreciate the response though buddy.

[Scrippy]

Found my issue! Both guibos are good but my carrier bearing is shot. Makes sense as I couldn't differentiate where the vibration was coming from (front, middle or back of drive train). No cracks at all on the front or back guibos so the huge crack in this carrier bearing bushing is my culprit. (2nd Pic attached). Question for those who read this……is this blow by/leak on my exhaust? (1st pic attached) the black marks look like gas escape points to me. Let me know if you have time.

[Helmsman]

Wow this forum eventually solves even the strangest issues om this car. Bloody good job done Scrippy!

Ps. All good on the dent and mad people side..?

[Scrippy]

Originally Posted by Helmsman

Wow this forum eventually solves even the strangest issues om this car. Bloody good job done Scrippy!

Ps. All good on the dent and mad people side..?

Hahaaa, I didn't solve it myself. There are like 6 prior threads that helped. I was just lazy pulling parts off. If I had a lift my post would have been "informational" instead of another "help" thread. Now I'm compiling my rebuild kit. All hardware will probably be replaced. I see a shim and a centering ring annnnnd… The guibo looks good but I'm here already so naturally thats gotta be replaced lol. Same thing for the trans mounts. It's looking like a $500 thing to do it right so far. I'm trying to suppress my OCD to areas or sections, otherwise it would end up being an underside restore somehow. Purl is 11 years old now.

[Richbot]

Originally Posted by Scrippy

None of my engine/trans braided lines are disconnected or green from oxidation. I'm a Cali resident so things don't wear/oxidize or moisture out as much here. Wouldn't a coil out of tolerance always throw a code? My confusion is no errors but the turbulence/vibration on hard acceleration. No tunes and nothing coded out, 100% stock. Totally appreciate the response though buddy.

Having not spent much time in socal until this past weekend this made zero sense to me but now I get it. Shit I think I saw one cloud the whole time, and was barely sweating in the 90 degree weather.

Coils going bad don't always throw codes but misfire codes are usually way before any noticeable drivability issues. I'm just talking keeping the car in top shape, but without a misfire code they're probably fine

Yeah that looks like a little bit of leakage, is there also black on the clamps? That'd be the giveaway

[Scrippy]

Originally Posted by Richbot

Having not spent much time in socal until this past weekend this made zero sense to me but now I get it. Shit I think I saw one cloud the whole time, and was barely sweating in the 90 degree weather.

Coils going bad don't always throw codes but misfire codes are usually way before any noticeable drivability issues. I'm just talking keeping the car in top shape, but without a misfire code they're probably fine

Yeah that looks like a little bit of leakage, is there also black on the clamps? That'd be the giveaway

Yeah that's what I was referring to, the lack of moisture lol. Not any crap like California is better than any other state. I don't drive my car to the snow and there has been snow where I live like 4 times since 1982. In Cali our cars are usually dry all year and don't have to face road salt. Hence the undercarriage is usually in great shape when compared to northern or eastern cars. To answer your question yes there was a little black eraser shaving like dust on the undercarriage trans tunnel. It was in the spinning pattern spread just behind the bearing parallel to rotation of the shaft. I wiggled the shaft and it didn't slop around excessively but that crack in the picture would certainly allow what I'm feeling on hard throttle pulls. I am renewing everything on the drive shaft except the constant velocity joint. Gonna do the trans mounts as well while in the work area. Just waiting on FedEx for my stuff