PT Cruiser Forum  
Advertisements
       

Go Back   PT Cruiser Forum > General Forums > Tech & Performance Forum

PT Cruiser Forum

Advertisements
Rough idle and high speed stumble / surge

 
Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 12 Apr 2013, 04:11 pm
Fresh Cruiser
 
Join Date: Mar 2013
Posts: 2
Default Rough idle and high speed stumble / surge

Hi all,
Hoping to shed some light on this PT's problem. Its a 2005 Touring non turbo, auto trans. It has 70,000 miles on it. Got it at 40,000 and within 6 months replaced the motor mounts and torque struts and had a corroded + battery cable that needed a new end. A couple weeks ago I got it back from my daughter (was a loaner for a few months) and noticed that it had a bit of vibration at idle and what appeared to be a slight water drip out of the WP area. The mileage was poor (under 20 Mpg) The lower pass side torque strut was toast again and I decided that it was time to do a tune up and timing belt / water pump replacement. BTW, I have 35 years experience in the auto repair field and am an excellent and very thorough mechanic.

Well, I did the timing belt and water pump and changed the sparkplugs for Bosch Plat+4s (the old plugs were heavily eroded - .60-.70 + gap) and installed a new air filter and lower torque strut. Upon the first test I noticed that the engine ran and started fine but as it warmed up (AC off) the idle became slightly rougher than I liked. It felt like a small vacuum leak, went right away when you broke idle. I then noticed that when I revved the engine to approx 3,500 rpm it would run out of steam and start "surging". At normal speeds it had good power, ran perfectly. No CEL, no codes. Hmm. Wondered if it was in learn or limp mode so decided to check codes and reset at the local O'Reillys and drive it for a day or so. No codes. Drove it around for a few days and while the idle quality was still not great and did seem to vary slightly but there was nothing I could pin down to being temp or mileage related etc. BTW, yes, I have checked all the motor mounts and struts and verified the cooling fan works in both speeds. Next couple times I drove it the CEL popped on randomly. Stopped and checked the codes and got a camshaft position sensor code which did not come back on until the next day and then went right away before I could get home. Checked the forums and decided to try a different set of plugs and went with the basic oem Autolight AP5263 platinum gapped @ .040. Felt there was a very slight improvement in idle quality but not enough to really make a judgement. Could have been the situational / intermittent thing. It still exhibited the surging and rough idle symptom.

Considering the symptoms I did a very thorough check for vacuum leaks and found none. Checked all the electrical connectors that could have been disturbed and found no wiring issues. Looked at the forums again and concluded that somehow I must have gotten the timing off a tooth or something so I tore the car back down and checked the belt. Sadly, it was just like pictured (1/2 tooth down on the exhaust with the intake level through the bolt holes, crank on the mark) and appeared to be perfect. That said, there seemed to be a couple of different opinions on the timing setup so I proceeded to reset the timing to match the pic Cruisin posted with the marks pointing slightly up just to see if I was misinterpreting or using the wrong info. Using this setup the engine ran very poorly and this was obviously not the answer. Reset the timing a couple more times trying a cog either way (yes, marked the belt and pulley) on both the intake and exhaust from the pictured scheme and in all cases the engine obviously ran worse so I have concluded that the pictured timing pattern is the correct one. Put it back that way, ran the engine (ran fine except for the slightly rough idle, no CEL) and have concluded that the problem must be something besides the timing and it appears to have manifested upon the belt / wp work. Putting the engine back together now and will check and clear the codes and then check for vac leaks again (I tiewrapped all the hoses etc) and then start another diagnosis loop.

I cannot afford nor do I trust the local Chrysler dealer to do a proper diagnostic on this as when I stopped by to inquire about paying for a diagnosis they immediately told me I needed a timing belt. When I told them it had just been changed and verified, they told me it was obviously still wrong and that they would need to change it using OEM parts "just to make sure" and the cost was rediculous. Hmm, I guess I was wearing my stupid hat or something, realized that I obviously had been doing things totally wrong at my repair shops down thru the years. NOT!

So to recap, I am damn sure the timing is right. I am using the OEM replacement plugs. I have no detectable vacuum leak. No wiring harness or plug issues (cracked while lifting engine etc). All the motor mounts are new or in perfect condition. I still have the rough idle and high speed surging issue. I am going to test drive, clear the codes and then discon the batt for 15 minutes and then test drive again. I have considered just shotgunning the cam position and map sensor but that just doesn't seem very professional. I am pondering finding a local independent shop that has the high end OBD reader and trying to get them to do a thorough diagnosis only but again, that is money I really don't have to spare if I can help it. It is fully insured tho. Hmm.

Any thoughts or advice? If I do try to get an independent diagnosis what is the correct machine to ask for? I have a $200 reader and I know it doesn't do everything.

Any help would be appreciated.
Attached Images
File Type: jpg Picture 8.jpg (20.8 KB, 19 views)
Reply With Quote
  #2 (permalink)  
Old 12 Apr 2013, 08:28 pm
Cool Cruiser
 
Join Date: May 2011
Posts: 228
Default Re: Rough idle and high speed stumble / surge

I too am having the same issue but I am throwing a PO302 code. I do not think its a plug or wires as they are less than a yr old. I was getting a hiccup now and then. Now I get a rough idle and flashing to steady light. I am going to check my MAP sensor, and EGR valve. I do not think its a plenum leak, or injector as the car runs fine other than at idle. I think these cars have a rev limiter which does not allow you to rev the engine when not in gear. Mine wont go past 4K. In gear she will rev to infinity.
Reply With Quote
  #3 (permalink)  
Old 13 Apr 2013, 12:01 am
Fresh Cruiser
 
Join Date: Oct 2008
Posts: 13
Default Re: Rough idle and high speed stumble / surge

I seem to have a similar issue. I have a 02 no turbo, 78K miles. Been running fine but coming back from a short round trip of 80 miles I come off the hiway and stopped and the engine was idling rough. I didn't notice any problems when driving only at idle. I used approx. a quarter tank of gas and have wondered if I possibly got some bad gas. It's been a long time since I have had a bad tank of gas but I guess it is still possible. It seems to accelerate fine it just has a rough idle. I am planning on siphoning out the gas and burn it in my CJ5 and fill up with a fresh tank and see what happens.
Reply With Quote
  #4 (permalink)  
Old 13 Apr 2013, 01:24 am
Senior Cruiser
 
Join Date: Jan 2013
Posts: 1,266
Default Re: Rough idle and high speed stumble / surge

CCC; the diagram you posted is for installing the belt only. After the belt slack is taken out, all timing marks must align. Inner cam sprocket marks must go thru the centerline of the cam bolts. There are some wrong pictures on this site. They are confusing many people. Also, the Haynes manual is confusing too.

The original plugs are champion RE16MC @ .040

Last edited by pt06; 15 Apr 2013 at 03:51 am. Reason: added 'sprocket'
Reply With Quote
  #5 (permalink)  
Old 13 Apr 2013, 03:19 pm
Fresh Cruiser
 
Join Date: Oct 2008
Posts: 13
Smile Re: Rough idle and high speed stumble / surge

Hello everyone, I would like to report that I believe I solved my problem with the rough idle. Getting to the spark plugs takes a little more work but I replaced them and the wires. The original plugs with 79K miles were pretty much burned up. when I started the engine it still idled rough but I thought lets give it a chance. I took it out on the hiway for about a ten mile ride and now it's purring like a kitten once again. For those with this issue I hope this will solve your problem. The auto store recommended to use some stuff on the threads to keep it from seizing up when removing the plugs again hopefully in another 79K miles or maybe that will be the next persons problem. Who knows I might still have it.
Reply With Quote
  #6 (permalink)  
Old 14 Apr 2013, 06:16 pm
Fresh Cruiser
 
Join Date: Mar 2013
Posts: 2
Default Re: Rough idle and high speed stumble / surge

Quote:
Originally Posted by L2fish View Post
I too am having the same issue but I am throwing a PO302 code. I do not think its a plug or wires as they are less than a yr old. I was getting a hiccup now and then. Now I get a rough idle and flashing to steady light. I am going to check my MAP sensor, and EGR valve. I do not think its a plenum leak, or injector as the car runs fine other than at idle. I think these cars have a rev limiter which does not allow you to rev the engine when not in gear. Mine wont go past 4K. In gear she will rev to infinity.
Yep same here. 3,750 in park reving in the work bay, pulls effortlessly to 6K on the highway. Then threw a Cam position sensor code. Changed the cam sensor for a bosch premium unit and still the same problem. Going to try and find someone that has the right scanner to correctly diagnose this pig. Sigh.
Reply With Quote
  #7 (permalink)  
Old 18 Apr 2013, 11:49 am
Young Cruiser
 
Join Date: Jan 2013
Location: On Vancouver Island, BC
Posts: 80
Default Re: Rough idle and high speed stumble / surge

Quote:
Originally Posted by CCCruiser View Post
Yep same here. 3,750 in park reving in the work bay, pulls effortlessly to 6K on the highway. Then threw a Cam position sensor code. Changed the cam sensor for a bosch premium unit and still the same problem. Going to try and find someone that has the right scanner to correctly diagnose this pig. Sigh.
CCCruiser how did you fix your initial problem? I am chasing that rpm ghost at ~3800 rpm.

As for throwing the cam sensor code, you might want to see if you can monitor the voltage. I ended up tracing a voltage pull-down issue to my IAC (which was not throwing a code), or more correctly, I should say it disappeared when I changed it and it has not come back.

My voltage pull-down indication was when any accessory was activated there would be a heavy RPM pull-down (down to almost 450/500ish) and it would throw the cam sensor code if I used the throttle.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Idle Surge Of Sorts? Oil Identity? GTCRUISER2006 Tech & Performance Forum 17 30 Jan 2012 06:45 pm
idle stumble themadgreek187 Tech & Performance Forum 7 17 Feb 2011 01:13 pm
surg type idle, and surge while driving katlady Tech & Performance Forum 6 12 Aug 2009 12:46 am
Hesitation\stumble off idle k9t8m Tech & Performance Forum 4 30 Jul 2009 07:06 pm
idle miss and boost surge mtnbktrek General Turbo Discussions 7 02 Feb 2007 04:08 pm


All times are GMT -5. The time now is 01:57 pm.




Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
LinkBacks Enabled by vBSEO 3.6.0 PL2 © 2011, Crawlability, Inc.
vB.Sponsors