Skip navigation

10 faults 1.8t 20v conversion HELP!!

Post

Back to the top

Wiring faults? Ecu problems?

Right, i bought a mk1 golf about 6 months ago when i bought it it had already been converted to a 1.8t 20v engine, the engine code is aeb. When i bought the car it was hesitating a bit since then i have threw money at it replacing a lot of things such as, fuel pump, fuel filter, all new loom conversion done by dubnutz, a new loom, replaced maf sensor, replaced turbo tip pipe, replaced bov valve, ran some new pipes radiator pipes, vacuum pipes etc, replaced all coils, have swapped injectors for another set that came with the car. I have literally tried everything to get rid of it. The first time i plugged into the car after having a loom conversion it threw one code which was a p0102 maf sensor low voltage, i then replaced the maf sensor with a brand new one and the car ran worse that before!! The origional maf which i believed to be knackered worked better than the brand new genuine bosch one. Whereas if i unplugged the origional maf it ran exactly the same and also the same if i unplugged the new maf it ran better. I have since then got hold of vagcom which has lead me to 10 different faults which has shocked me and i really dont have a clue where to go from here? Anyone have any ideas what these faults could be or know of anyone i can take it to to sort them out for me? Many thanks, this is my first post on the forum also so am getting used to it at the moment so bare with me 🤣🤣 20190504_124421.jpg

Post

Back to the top
Have you checked the ecu?

Post

Back to the top
I havent and i also have no idea how to do this 😂😂

Post

Back to the top
Where is the ecu located in the car? Some conversions do not extend the wiring so the ecu is sometimes left in the engine bay so can suffer from over-heating, water ingress e.t.c.

You can send the ecu off to an expert to be tested (I don't know anyone to recommend myself, hopefully someone can chime in or google). Your options on ecu:
1. Send ecu for test & repair - cost unknown
2. Buy 2nd hand ecu (£25 on eBay)  & have immob deleted (£25) - cost £50
3. Buy 2nd hand ecu (£25 on eBay) & have immob deleted & remapped to circa 200bhp - cost £150'ish
4. Borrow an immob deleted AEB ecu off a friend or forum member - cost £0 but this is not the most common of engine codes so you'll be lucky if someone has one handy 

If you can find a company to just test the ecu, then if found faulty repair usually quite expensive. Option 2 cheapest option to replace in this case

Last edit: by Cushti

Post

Back to the top
Your ecu is toast  pal wouldn't be wiring if all them codes coming up a1.8 t ain't that unreliable  .you probably got water in ecu

Post

Back to the top

Cushti said

Where is the ecu located in the car? Some conversions do not extend the wiring so the ecu is sometimes left in the engine bay so can suffer from over-heating, water ingress e.t.c.

You can send the ecu off to an expert to be tested (I don't know anyone to recommend myself, hopefully someone can chime in or google). Your options on ecu:
1. Send ecu fit test & repair - cost unknown
2. Buy 2nd hand ecu (£25 on eBay)  & have immob deleted (£25) - cost £50
3. Buy 2nd hand ecu (£25 on eBay) & have immob deleted & remapped to circa 200bhp - cost £150'ish
4. Borrow an immob deleted AEB ecu off a friend or forum member - cost £0 but this is not the most common of engine codes so you'll be lucky if someone has one handy 

If you can find a company to just test the ecu, then if found faulty repair usually quite expensive. Option 2 cheapest option to replace in this case



Would i have to replace the ecu with the same on or can i use an agu ecu? Also my car is running a k04 and uprated induction etc and uprated injectors so i dont suppose buying an ecu that is remapped to 200bhp is worth it as i would need a custom remap wont i? I have been looking st remaps for a while but wanted to sort the engine out before i do it as i have no proof the ecu has been remapped before tbh with you. Or would i just be better off getting the standard ecu with immo delete? Cheers for your response 👍

Post

Back to the top

nick flude said

Your ecu is toast  pal wouldn't be wiring if all them codes coming up a1.8 t ain't that unreliable  .you probably got water in ecu

Brilliant i will start looking at ecus then mate cheers 👍

Post

Back to the top




Cushti said

Where is the ecu located in the car? Some conversions do not extend the wiring so the ecu is sometimes left in the engine bay so can suffer from over-heating, water ingress e.t.c.

You can send the ecu off to an expert to be tested (I don't know anyone to recommend myself, hopefully someone can chime in or google). Your options on ecu:
1. Send ecu for test & repair - cost unknown
2. Buy 2nd hand ecu (£25 on eBay)  & have immob deleted (£25) - cost £50
3. Buy 2nd hand ecu (£25 on eBay) & have immob deleted & remapped to circa 200bhp - cost £150'ish
4. Borrow an immob deleted AEB ecu off a friend or forum member - cost £0 but this is not the most common of engine codes so you'll be lucky if someone has one handy 

If you can find a company to just test the ecu, then if found faulty repair usually quite expensive. Option 2 cheapest option to replace in this case

Also the ecu is under the dashboard

Post

Back to the top
If you have all those mods then getting another AEB ecu will be no good. Like you said your engine needs a custom map as the AEB never came with the K04 or other uprated injectors. Also you cannot use other engine code ecus instead.

You need to speak to an 1.8t ecu mapper & ask for advice. They can test your current ecu & go through your options if it's at fault. 

Post

Back to the top
Brilliant, thanks for all the help mate youve been spot on with your advice, ill take it from there and let you know how i get on, onve again cheers for the advice.

Post

Back to the top

Cushti said

If you have all those mods then getting another AEB ecu will be no good. Like you said your engine needs a custom map as the AEB never came with the K04 or other uprated injectors. Also you cannot use other engine code ecus instead.

You need to speak to an 1.8t ecu mapper & ask for advice. They can test your current ecu & go through your options if it's at fault. 


Have just googled that ecu and it seems like it is off an agu engine not an aeb engine…

Post

Back to the top
Too many things it could be. A couple of reasons could be that the current ecu could have been custom mapped to the engine & it's just gone faulty, perhaps the engine has never run right as it's just a stock ecu that doesn't recognise the K04 & injector upgrades.

The ecu needs to be checked out in my opinion & a expert should be able to tell if it's got a custom file on it and/or if it's faulty

Post

Back to the top
Have bought a new ecu and de immobilised it, the car still runs exactly the same with hesitation and backfiring etc, it is also still the same in terms of the maf sensor being plugged in it runs worse, which now leads me to believe the wiring is knackered...

Post

Back to the top
Has the new ecu been mapped to the upgrades? Do you have a friend who can run the diagnostics again for you? Otherwise a scanner only costs about a tenner.

If the engine runs better with a working Maf unplugged then that can mean many things but my experience with this has usually led to a dodgy O2 sensor or vacuum leak. Have you checked the inter-cooler & hoses yet?

Post

Back to the top
you could probably run live data
using vag com that would probably
eliminate the guess work if the car
actualy a runner

Do not know a lot but willing to help if possible

1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF

Post

Back to the top
This may sound daft but if ecu ok and  not sure weather you bought the car as a project but timing could have been set half a tooth out which can be easily done on 1.8t and cause these symptoms 

Post

Back to the top
You have a number of variations on the 20vt cars and best bet is to modify an ecu as close to the set up you have on your conversions.

For example, these are the main maf maps of various ones and as you can see they are different, using the wrong one therefore will knacker your air flow monitoring up stright away and obv. with the air/fuel aspects this is a bad thing.

Old Motronic, none ME fly by wire like the older AGU's can be quite different than the newer ME7 stuff, you can see how the map is not related to a direct voltage like the two newer ones, you can see 2 different flow rates on the newer ones due to size difference of maf/hfm;

1.8T MLHFM by Rick B, on Flickr

So, say you use an S3 maf and are using a k03 engined car with ME, you can copy over the values from the S3 maf with the higher flow rate to the middle one your ecu would be set up for. Same for fuel and so on as a quick way to match up a k03/k04 mish mash of parts.

Once your air and fuel maps are sorted like that, then you go through what parts you are/aren't using in the conversion, VVT ecu and a none VVT engine for example, you modify it to suit and so on.

Rocco S3 variant files by Rick B, on Flickr

I'd say the best fix is to use a pedal box and get an ME7 ecu, either k03 or k04 doesn't really matter, but try and match the engine, so if you are running old Motronic and are using a none VVT engine, get a none VVT but newer ME7 ecu as it is nearer to spec and less to change.

You can get a cheap MPPS V13's or I'd get a V18 if you can afford it. Then you can read the ecu and have access to everything to change then, it'll save time and effort in future too for remote tuning and they have a checksum button.
If you change to ME/Pedal box, get an immo off ecu and get a read when you plug it in your car, get a list of code faults and work from there, these will generally be;
 - VVT or not, fly-by-wire or not (M vs ME Motronic), maf/hfm size, injector size, 02 sensors/heating/cats, SAI/EVAP's and then some possible wiring/ABS and the like dep on your conversion - a complex one may take a half hour/hour or so on the ecu if you know what you are doing and have a good def file if you do it yourself.

Last edit: by mk1-400

Post

Back to the top
had similar issues with my 18t ended up being the ecu, I needed to get a number of sensors deleted and the ecu update, ended up taking it back to standard to start over now running much smoother .
0 guests and 0 members have just viewed this: None.