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View Full Version : 97 1.8 Non Turbo Rough Idle / Hesitation



RobNorwich
15-04-2006, 07:58 PM
Hi everyone, Im new to this site and new to Volkswagen having recently purchsed a 1997 1.8 20v Passat. Until now I have been a "Ford" only guy but having driven my partners passat I am now a VW Convert.

My problem is this:- The car does not idle smoothly, its lumpy and feels like a misfire or as tho the ECU is constantly trying to change or correct something. There is a definite hesitation on acceleration but this seems less pronounced once your past 2000 rpm - if you open the throttle from say 1500 rpm there is a brief spurt of acceration followed by a definite hesitation - then it clears and off it goes right up to red line if you let it. I would emphasise that this is the NON turbo engine. The car also has a rich smell to the exhaust.

Had the codes read today and there was a mention that something within the throttle body was "at the limits of travel". The guy didnt really exlain too well what it was but im assuming its something like the idle speed control side or the throttle position sensor? He said that the throttle body would require removal and cleaning. Once done he said that the ECU would need re programming to set the upper and lower limits for "the parameters" In total this would cost me 80 quid if he did it (2 hrs lab & 30 quid for code read/set). Last night after a run the engine was very reluctant to be revved and felt like it was flooding. There is no feel of misfire when you have gone beyond the RPM where you get hesitation.

My question is does this sound like a dirty throttle body to you? Would it cause hesitation as described? And is cleaning likely to resolve it? Also does the ECU Really need setting or would removing the battery for 30 mins not allow the ecu to re learn the paramters?

To me this feels (and smells) like a failure in the Hego sensor or the TPS - but neither have triggered a fault code. Air Mass has also been mentioned and one guy suggested I disconnected it and drove the car - I did this despite not really wanting to trigger any more codes yet the car stil drove exactly the same - no change.

Sorry for the long posting - im just trying to be as precise as possible. PS Car has full s/h and has plugs and oil in last 4 weeks.

Cheers Rob

RobNorwich
22-04-2006, 04:16 PM
Well im not sure if anyone is following this thread or not - but I will post my findings regardless as it may be of help to someone oneday. I have got myself a Vag-Com at last - we run 2 Passats in the family so I saw it as a good investment long term.

The fault was as follows:-
Control Module Part Number: 8D0 907
Component and/or Version: 1,8L R4/5V MOTR HS D03

2 Faults Found:
17916 - Idle Control Sys: Upper Regulation Limit Reached
P1508 - 35-00 - -
01120 - Camshaft Adjustment 1
04-00 - Mechanical Malfunction

Fairly clear problem - the camshaft/valve timing adjustment is not taking place as it should - I guess the system is stuck in the higher rev range mode - hence being flat below 2000 rpm but fine above that.

Anyway, after having numerous people try and convice me the problem was air mass meter related I decided to investigate further.

Vag-Com was put into output test mode on the engine components (injectors, EGR, camshaft adjustment etc) I heard all of the various items actuate APART from the cam adjuster. Removing the solenoid from the cam adjuster showed the solenoid is receiving the signal from the ECU but the oil valve inside the block of the camshaft adjuster was jammed fast so the solenoid could not adjust the oil flow to the actuator system that does the adjustment under the rocker cover.

I managed to move the valve and tried some WD40 but its not having it. I now have it so that the engine is running much better but is still logging the code as above - must have moved the valve to the mid position.

Has anyone had any experience of changing the camshaft position actuator - it looks like both cams need to be removed but im not entirely sure?

Idle is now much smoother, no hunting at all and the hesitation is improved. Its still not right so I will get it sorted - just wanted to try and save a few quid if possible.

PS. VW Main Dealer more or less DENIED that the camshaft position actuator existed and tried to sell me a MAF sensor for £100. Having checked the sensor live data from Vag-com while driving - its returning almost exact figures as a known good Passat with same engine. I was also told by same dealer that its not possible to obtain live data from the sensors using the equipment I have - oh well! :D

Any comments ??


Rob

Gavin78
05-01-2007, 12:54 PM
Rob,

I have just seen your post from Last April as I am suffering a similar engine misfire/hesitation with my '98 NON TURBO 20v. For some time I have been experiencing an intermittant lumpy tickover and hesitation/engine cough at about 2600ish RPM while accelerating. More recently I have had a minor accident (light front damage) which has resulted in a constant misfire on tickover though this is unnoticeable once I pull away and get up to speed. I am getting a little frustrated as I have just gave the car a basic service (plugs, oil, filter etc) thinking this would slove the problem - it didn't!!!!

Gavin.

JHT
10-01-2007, 01:55 PM
Mine has the same symptoms, with no fault codes. I have been chasing the fault for a while now, with little success. Will look at valve timing though.

davo79
29-03-2007, 06:10 PM
Hi,

I have got an Audi A6 2.4 This has a rough idle. I have changed the plugs and the flow meter and the computer has no codes. I see you may have had similar. How did you get on?

Regards,

Dave.

Gavin78
29-03-2007, 07:03 PM
Yours is a completely different animal Dave, I have only ever had 4 cylinder Passats so would be of little help. All I can suggest is that you get it plugged into VAGCOM and read the codes. If there are any codes, post them on the forum as others may be able to offer some advice.

Gavin