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YOUR RESEARCH`02 C4 judder/missfire
Leading reported evidence
Check twice now and also still no warning lights
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No successful repair reported for this finding.
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Performed · outcome unconfirmed · Original poster
OPC checked twice now and also still no warning lights.
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Suggestion · Original poster
I have no codes or check lights on...no issues flooring at high revs, only when accelerating at low revs (not even necessarily flooring, maybe half throttle or more at low speed)....and when on light throttle at low speeds no judder but slight feeling of `surging` as if fuel coming and going.
Leading evidence: 'Check twice now and also still no warning lights' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check lights' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
It is an easy thing to get to and can be cleaned quickly with a liberal spray of contact cleaner.
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Performed · outcome unconfirmed · Original poster
Plugs and coil packs replaced...and i dont like to give up until I`ve tried all I can first Vinny :lol:
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Suggestion · Original poster
I have no codes or check lights on...no issues flooring at high revs, only when accelerating at low revs (not even necessarily flooring, maybe half throttle or more at low speed)....and when on light throttle at low speeds no judder but slight feeling of `surging` as if fuel coming and going.
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Suggestion
First off you need a fault code check on the DME ..
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Check lights
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
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Suggestion · Original poster
I have no codes or check lights on...no issues flooring at high revs, only when accelerating at low revs (not even necessarily flooring, maybe half throttle or more at low speed)....and when on light throttle at low speeds no judder but slight feeling of `surging` as if fuel coming and going.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
911uk: 1 discussions
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HELP!...Hi all. I`ll try to put this into words. My manual C4 has an issue which happens only when i open the throttle quite wide at low speed in high gears (not labouring). Initially thought it was coils but replaced these and plugs at the same time. No difference. I`m now even thinking along the lines of flywheel failure but dont have clutch judder when pulling away which confuses things further. It`s a fairly pronounced `judder` I`d call it.No warning lights, no problem on light throttle input in 3/4/5 etc but if i push the pedal half or more i get this `judder/misfire` feeling. only other thing I`ve noticed is an almost surge like feeling accelerating on light throttle (almost like i was lifting my foot off/on accelerator). Any known issues with injectors or any other ideas greatly appreciated. Cheers.
First off you need a fault code check on the DME .. if no codes then something is failing that's not monitored or something is within the set limits but not correct .
To test for flywheel .. drive the car at almost stalling speed 1st gear .. you will get a judder if the flywheel ( DMF ) is faulty .. that doesn't seem to be your problem ..
if you floor the car at high rpm do you have an issue ? is it only at low rpm and floored you have this juddering ?
Coils etc will give a fault code for misfires hence the need for this check .. running problems and the same again .
juddering can be anything from engine mounts to low fuel pressure so hard to diagnose but a failing fuel pump is possible .. to be fair atm with the info i have i can think of many things .
fault code readout is a starting point .. no codes does help to a small degree but a code helps a lot more .
Hi deMort. Thank you. I have no codes or check lights on...no issues flooring at high revs, only when accelerating at low revs (not even necessarily flooring, maybe half throttle or more at low speed)....and when on light throttle at low speeds no judder but slight feeling of `surging` as if fuel coming and going. Not engine mount related (these are new gen ones). It felt like coils breaking down so was surprised when new ones didnt fix the problem.
Difficult to ascertain atm whether this is an engine fault or something like a gearbox mount issue .. if you did a video would it show anything that might help us ?
If we go with engine issues then things like a misfire will generate a fault code and you don't have any codes .. i would still wonder about spark plugs and when they were last changed though .
With no fault codes then the only things not covered are fuel pressure and CPS signal .. CPS is very unlikely and with fuel pressure you would normally have an issue with Full throttle and a lack of power .
Half throttle at low speed and the engine is under high load .. that would be the point a coil or plug could break down but i'm guessing here ..
For me i would have a tester on the car and look at some of the values from lambda sensors to maf to rough running on each cylinder and go from there .
A garage read out the fault codes .. did they investigate the issue at all ?
Just an idea......
If it could be described as a flat spot rather than a judder it could be a dirty MAF.
It is an easy thing to get to and can be cleaned quickly with a liberal spray of contact cleaner. Let it dry for 15 mins, reinstall and see what happens.
C
A few ideas
Hi,
With no codes, it makes life harder.
Could be a number of things.
- MAF (clean or replace)
- Coil Packs
- Crank Position Sensor
- Plugs
- Cats (Doubt it is)
Book it into a good Indy. They will have far more experience and work through it.
Where about's are you located?
Vinny
dont know if this makes any difference but been out today and deliberately trying to make this happen. Definitely nothing i can feel wrong at higher speeds and full throttle but at low speeds even on lights throttle the car seems to feel hesitant/stuttery (not undriveable at all but easy to feel) and also thi sort of surging feeling when trundling along then accelerating gently. Almost like i was moving the pedal up and down slightly. :dont know:
Ok .. both rare issues and i'm not sure how to diagnose without replacement so i'm just throwing this out there ..
The throttle has plastic gears inside .. these can wear , get damaged .. throttle will have an altering angle due to this .. very rare !!! .. i've done 1 in 18 years .
High lift tappet solenoids .. one on each bank .. they should throw a fault code for misfires on the bank its messing around on .. it will give rough running below 3K rpm .. above that value it will run fine .. light or hard throttle input .
I certainly don't want you throwing these items at your car .. i'm merely mentioning its possible .
for me .. i would have a tester on the car and look at the live values of the sensors before moving onto replacing items .. that's what i would suggest .
I've fixed cars purley from values .. and i've fixed them from feeling what the car is doing .. Porsche tech whilst i realise there are not so many in your neck of the woods so i'm told might be the best option .
Thank you. I`m just going to have to bite the bullet and get it in somewhere...or stop being lazy with the gears and use it until i have a warning light on :dont know: :lol:
So,after monitoring mine for a while now, my description has changed. This only happens when picking away slowly from standstill or driving with foot at light throttle the car is `juddery, stutters` but more throttle application stops this. Only seems to be the first 1" or so movement on accelerator pedal. Possible worn potentiometer? I have no codes. OPC checked twice now and also still no warning lights. I`ve just done around 800 miles to C&M, then Diddly Squat with no issues other than this. The car is always on Vpower and I`ve also tried an injector cleaner :?
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