Problem with A4 1.8t

liam_mcf

liam_mcf

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Hi, not long registered to the site so hello, been reading for the last week or so :sm4:

Bought a 1996 A4 1.8t only a few days ago, everything was running smooth till yesterday morning. When i stopped at lights and at idle the car felt a little shakey, a bit like a diesel engine, when i pull away up till about 3rd gear it feels like its loosing power! When im up and away it seems ok.

It was the same after i stopped a few times then pulled away, then after a few times i stopped again and at idle i could feel the shaking then all of a sudden it stopped and sounded fine, and it pulled away fine, this only lasted a while then it when back to the shuddering and shaking...

Seemed to come and go throughout the day. Not tried again today yet as im at work.

Anybody any ideas? I ordered one of the cheapo Vagcom leads from ebay yesterday, so ill check if it has thrown up any fault codes when it arrives.

Could it have been the person i bought the car from new this problem was there and hid it well? As i've said only had the car 3-4 days.

These are the days i wish when i done my apprenticeship years ago it was for a mechanic and not an electrician haha :keule:

cheers
 
The shakeyness sounds a bit like a missfire.

There are some common culprits (the ignition amplifier or coils) but i'd be looking at the basics first like the spark plugs, the only odd bit is that it goes away in higher gears, as usually a missfire would become more pronounced under load.

If they've not been changed recently then i'd pickup some BKR6E's, ensure they're gapped to 0.028" and install those and see how it goes.

Might be worth giving it a service if it hasnt had one recently, oil and filters etc.
 
Thanks for the info.

I'll pick up those plugs later on today and change them later and see how it goes!

Going to put the car in for a service sometime next week, thankfully i have a works van at the moment so if changing the spark plugs doesn't do the job i'll not be using the car till its sorted!
 
oh and aragorn, what are the BKR6E's gapped at normally?

Jumped out and bought a set on my break there, but the gap looks big! Just gonna dig out a feeler gauge and give them a measure soon.
 
I'd probably go with the ICM, coil packs or throttle body. Probably likely the throttle body though if it goes at higher revs.

Can you tell if it is a misfire or more like your engine is hunting for revs?

If it's hunting then my money is on the throttle body.

A scan for fault codes would be best so maybe wait until you've got your lead until you throw any more money at it.
 
Thanks mate, yeah i'll change the plugs if there is no difference i'll wait till the lead arrives and see what happens, will put it through a service soon too.
 
I'm not sure on the standard gap, but you want 0.028" or 0.7mm.

As i said, ICM (ignition control module) is a common culprit for this kinda oddity, but the sparks are cheap so you'll want to ensure they're in good condition first.
 
Na Byzan there isn't, but i'm sure ill find someone

Ok cheers aragorn i'll change the plugs tonight
 
screw down coil packs or push in ones?
 
jcb said:
screw down coil packs or push in ones?
Click to expand...

There screw down, each with 2 hex screws.

Went to change the plugs, there is a problem with one plug though, it won't come out, it seems stuck, very stuck! The other 3 came out no problem, dont want to force this last one incase i damage the threads!

So i'm not sure what to do now....looks like i might need to take it somewhere, if i can't get it out i'm not sure how anyone else can :think:
 
hmm this is a tricky one.

More torque is probably required :D but then if its REALLY stuck you may strip the threads in the cylinder head.

Perhaps a little WD40 or similar down the plug hole to ease things along?
 
aragorn said:
hmm this is a tricky one.

More torque is probably required :D but then if its REALLY stuck you may strip the threads in the cylinder head.

Perhaps a little WD40 or similar down the plug hole to ease things along?
Click to expand...

Yeah was thinking that, will try tomorrow!! Thats what i was scared of doing stripping the threads, hopefully will come out :)
 
take it to a dealer.
yes they may charge you £40 and hour but if they wreck your cylinder head you are at least covered!

just take it in for a "simple plug change"....
 
i wouldnt trust a dealer as far as i could throw them tbh.

They'll either cover it up or just claim the fault was pre-existing and land you a nice bill.

When the engine dies 4000miles later because they filled the bore with swarf from retapping the head, your not going to get them to accept any liability for it...
 
Yeah its a hard one alright, my first reaction was to take it somewhere, will try some WD40 either tonight or tomorrow see how it goes!
 
it sounds like the prob i had an mine was the coil pack. a new one cost me £200 fitted. as far as the plugs go slitly warm the engine up with wd40 sprayed down the hole and some times it makes it easier to get it out.
good luck mate
 
stub said:
it sounds like the prob i had an mine was the coil pack. a new one cost me £200 fitted. as far as the plugs go slitly warm the engine up with wd40 sprayed down the hole and some times it makes it easier to get it out.
good luck mate
Click to expand...

OUCH !! Thats a lot of money fr just a coil pack change, you could have bought an entire set with plugs for that.
I do agree with slightly warm idea, be very careful though as warm alloy heads strip very easily. Plusgas, wd40 or similar soaked overnight then try the next Morning
 
ok so sprayed a good bit of WD40 in the plug, and took it good drive to my uncles to heat the engine up, got there and managed to get it out, for a moment i didnt think it was coming! The other plug went in no problem so thankfully there was no damage to any threads haha.

Anyway thats the plugs changed and took it for another run, still running badly below 3000 revs, looks like its misfiring to. Every so often though it comes back to life and you can feel the power and the engine sounds sweet.

I hooked up Vagcom so here is the errors its picked up -

Address 01 -------------------------------------------------------
Controller: 8D0 907 557 T
Component: 1.8L R4/5VT MOTR HS D03
Coding: 04001
Shop #: WSC 00000
5 Faults Found:
01262 - Solenoid Valve for Boost Pressure Control (N75)
26-10 - Output Open - Intermittent
17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting
P1564 - 35-10 - - - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 - -
17967 - Throttle Valve Control part (J338): Fault in basic settings
P1559 - 35-10 - - - Intermittent
16502 - Engine Coolant Temp. Sensor (G62): Signal too High
P0118 - 35-00 - -

Anyone any ideas? I was going to upgrade the dump valve anyway with the upgraded one, got a price of £26 from local dealer, are these easy to fit? Anyone any ideas about the other faults? I know there is a problem with the Immobilizer as the light sometimes flashes, but it starts no problem though.
 
Ok so i sprayed a good bit of WD40 down where the plug was, took it for a good drive over to my uncles, then tried again to get the plug out, eventually it came out haha, for a moment i didn't think it was gonna come. So im glad about that. So all the spark plugs have been changed.

Took it for another run, still running badly though, especially below 3000 revs, but at times it goes back to normal and you can feel the power and the engine sounds like it should!! There is a misfire when its running badly im sure.

Anyway just hooked vagcom up and got a few error codes here they are -

Address 01 -------------------------------------------------------
Controller: 8D0 907 557 T
Component: 1.8L R4/5VT MOTR HS D03
Coding: 04001
Shop #: WSC 00000
5 Faults Found:
01262 - Solenoid Valve for Boost Pressure Control (N75)
26-10 - Output Open - Intermittent
17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting
P1564 - 35-10 - - - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 - -
17967 - Throttle Valve Control part (J338): Fault in basic settings
P1559 - 35-10 - - - Intermittent
16502 - Engine Coolant Temp. Sensor (G62): Signal too High
P0118 - 35-00 - -

I see the first one about the Boost valve, im guessing this is the dump valve? I was planning on changing it with the upgraded one anyway, got a price from the dealers, £26! Are these easy to change? I noticed the Immobilizer one also, i do notice the Immobilizer light flashing sometimes but it starts ok! Anyone else got ideas about the others?
 
boost valve is the N75, not the dump valve, its a little block with some pipes and a wiring connector, just below the PCV valve on the inlet tract.

Coolant temp sensor error will make it run like crap too.

You need to discover if these faults are still present, by resetting them, then having a drive and seeing what comes back.

The N75 fault and the CTS could be the wiring or the part itself. I had that intermittant fault code for my N75 and it was faulty wiring.

Clear the codes and see what comes back.
 
Well i cleared the faults and the same fault codes seem to be there when i took it for a drive again!

I'm guessing i'm clearing them correct, in vagcom where it shows the list of faults on the left hand side you just press clear faults? They then disappear
 
Yup, so that would mean they are all current existing faults that you need to sort out.

Replace the CTS first of all, they're only around £20, and quite a common fault.

The N75 is a bit of a guessing game, either the valve or the wiring. I'd try getting another valve, or even a loan of a known good one, and see if that clears the code. They're about 40quid new iirc so a bit more pricey to change if its fine. If its the wiring you'll need to get a plug out of a car in the scrappy, cut yours off and solder it in.

The stuff about throttle valve is odd, although ive seen the same codes on craigs S4 when its TB was humped. Try clearing the fault codes, turning the ignition off, waiting a few seconds then turning it back on and waiting. You should hear the throttle body whirr and click for a few seconds then stop. After it stops rescan for codes. If they're still there its gonna need another TB.

On the 1.8T it has a cable throttle, but uses a stepper motor to open the throttle butterfly at idle, these errors point to the stepper motor and its sensor being unable to calibrate itself, and therefore the car wont idle properly as a result.
 
Cheers Aragorn

I'll try and get these faults cleared, no doubt ill be back with more questions soon

:keule:
 
Ok so i've been working away for a couple of weeks, not got round to sorting this problem so i'm going to start now!

Does anyone know the part number for the Coolant Temp Sensor? Would like to pick one up and replace this asap. 1996 A4 1.8T AEB engine.

Also is the sensor easily found in the engine bay?

Thanks
 
I'm going to follow this thread just in case it happens to mine.

I had a similar problem on a '96 Mercedes C280 Sport and it was a dodgy coil pack. They do seem to be common parts to fail over a wide variety of cars... my girlfriend even had one go on her Hyundai Coupe (thank God she got rid of that!).
 
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