Engine Over-Revving

nerox · Post by **nerox** » Sun Jan 06, 2013 3:29 pm

when i put the clutch down to coast upto some lights the rev's are staying up at about 1500 but as soon as i come to a complete stop they drop down to normal about 1000

i've checked the bellows tube on both the IM and the TB and seems secure with no splits.

throttle cable doesnt seem to be sticking .

what else could the problem be?

Kelevra · Post by **Kelevra** » Sun Jan 06, 2013 3:37 pm

your IAC could be sticking open? though when I coast in neutral in my ATX the RPMs usually stay a little higher then normal/idle when I'm still moving. possibly something to do with not slamming it back in gear low engine rpm meets high rpm speed?

Hudson_Neon · Post by **Hudson_Neon** » Sun Jan 06, 2013 3:55 pm

that's cause you have an atx... completely different man

check for vacuum leaks. take a can of starting fluid and spray down all hoses to find it

nerox · Post by **nerox** » Mon Jan 07, 2013 2:07 pm

Hudson_Neon wrote:check for vacuum leaks. take a can of starting fluid and spray down all hoses to find it

just tried that ... nothing happened, also wiggled all the hoses hoping to hear some revving if something moved causing a leak ... again nothing :\

Post by **occasional demons** » Mon Jan 07, 2013 3:19 pm

Did you have your battery unhooked when you were messing with the clutch stuff?

nerox · Post by **nerox** » Mon Jan 07, 2013 3:45 pm

Nope, hasn't been disconnected for months

jckevns · Post by **jckevns** » Mon Jan 07, 2013 3:54 pm

nerox wrote:Nope, hasn't been disconnected for months

Try disconnecting it for a bit, maybe the computer needs to reset

sidepipe87 · Post by **sidepipe87** » Mon Jan 07, 2013 6:54 pm

It is possible that your throttle plate is sticking slightly. I had that issue on my srt swap and people swore up and down it was a vac leak and I could never find one. Finally I decided to try adjusting the throttle plate screws and that solved the issue. Just a thought.

Post by **occasional demons** » Tue Jan 08, 2013 7:36 am

The only reason I asked, is because sometimes when mine has been disconnected for a bit, the in motion idle will be on the higher side for a day or so. Then it settles back down. Tho that was more of a problem with the non R/T pcm. Altho I have since'd replaced the TPS. Might have been a very early symptom. ::shrugs::

ZeroChad · Post by **ZeroChad** » Tue Jan 08, 2013 9:37 pm

My notes from troubleshooting the problem
viewtopic.php?t=24495

Post by **occasional demons** » Tue Jan 08, 2013 9:59 pm

Wow, that was a blast from the past.... Too bad those IAC's aren't available any more. I should have bought 5 of them before I posted that link.

Nerox, I thought of something, reading through that link. Not sure how they ran the vacuum lines, or how emissions are over there. It depends on where the LDP purge flow solenoid is mounted.

On our '00 - '02 it is under the brake booster. Not sure if they just left it on your passenger side, or just mirrored ours. But there is a vacuum line that runs from below the throttle plate, to the purge flow solenoid. Possibly it got bumped loose with removing the clutch lines to bleed them.

nerox · Post by **nerox** » Sun Jan 20, 2013 1:44 pm

interesting, ill have to look into that.

today on my journey the CEL came on and gives P0551 - power steering pressure switch i believe.

i wonder if its relates :s

Post by **occasional demons** » Sun Jan 20, 2013 7:39 pm

Shouldn't. The PS switch will raise rpm when enough pressure in the system is encountered, to keep the engine from stalling. Like when you are parking, or turning while moving slow.

If you don't want to mess with swapping the sensor out right away, but want the CEL to stay away, you could just unplug the connector, and wrap it up good in electrical tape to keep it sealed. Or buy a replacement, plug it into the connector, wrap up out of harm's way.

Mine hasn't had an installed sensor since I changed racks. because it is a newer ATX rack, and they don't have the sensor. I haven't had a problem. It handles turning/parking just fine. I just plugged the sensor into the connector to keep it clean.

blueneo03 · Post by **blueneo03** » Fri Mar 22, 2013 11:05 am

did you ever get a solution to this problem? mine is doing the same thing and its kinda annoying

nerox · Post by **nerox** » Sat Mar 23, 2013 4:23 am

blueneo03 wrote:did you ever get a solution to this problem? mine is doing the same thing and its kinda annoying

not yet, also it seems the problem has quietened down a bit, it still holds revs while coasting but only about 1100 instead of 1600, i cant quite figure out what might be wrong, although IIRC it started out when i took the TB - IM tube off so maybe its leaking. but nothing i can think of explains why it stops as soon as the car is stationary

nerox · Post by **nerox** » Fri May 03, 2013 3:08 pm

Today i replaced the IAC valve and the TPS but still not resolved

Fuzzyneon · Post by **Fuzzyneon** » Fri May 03, 2013 6:07 pm

having similar issue sticks at 1500 ish till i stock and when driving is "hangs" briefly if im below 3500 rpms gonna dig into it this weekend i will let you know what i find

Post by **occasional demons** » Fri May 03, 2013 9:00 pm

Check the TPS voltage - throttle shut. It should be in the 0.6 volts range.

I know when I was experimenting with the TPS position on my 60mm TB, raising the TPS voltage also made the in motion idle very high. So I put it back to the normal position, and it returned back to the usual 1000 rpm when moving.

nerox · Post by **nerox** » Thu May 16, 2013 2:01 am

Fuzzyneon wrote:having similar issue sticks at 1500 ish till i stock and when driving is "hangs" briefly if im below 3500 rpms gonna dig into it this weekend i will let you know what i find

Come up with anything?

blueneo03 · Post by **blueneo03** » Thu May 16, 2013 11:30 am

I solved mine.... i had messed with the TB and when i re assembled it left a slight gap that kept it open. so i re-set the plate and it fixed it!

nerox · Post by **nerox** » Sat Jun 29, 2013 12:08 pm

Replaced the PS pressure switch this morning ... quite possibly the easiest repair EVER on a neon.

haven't had enough time yet to see if the issue is fixed

nerox · Post by **nerox** » Fri Jul 12, 2013 4:34 pm

it's not fixed .... still the same as before

at least my CEL has gone but its still irritating