Hi All We are having real problems with getting my friends ABF to run correctly and we have a holiday booked for Friday to Drive to Devon About a month ago we completed an ABF conversion on his CE1 Mk2 golf. Initially we could not get the car to start and idle, this turned out to be the ICV, we used the ICV from my car (Also an ABF Mk2) to prove this, and eventually managed to get a spare to work. Next issue was that the engine would misfire and run rough after 2000 rpm up until about 3500 rpm. Again we solved this by changing the ECU Relay, also checked all parts on my car and replicated the fault. Now we have a new issue which is driving us crazy. If you start the car it idles fine, although at about 1100 rpm. However if you rev the engine the idle will not stop below 2000rpm, this is the same with the engine hot or cold. We have tried to squeeze the ICV feed pipe and this reduced the RPM until we let go, so we have concluded the ECU is telling the ICV to bypass to much air due to a sensor fault. With this in mine i have plugged in VCDS and check the throttle angle sensor is all ok, reads 0 to 73 degrees smoothly, the throttle closed switch is testing ok with a meter and the earth is good, i think the other wire feeds back to the ECU? is this correct. Would the throttle closed switch or its wiring being faulty cause the idle to sit at 2000 rpm? Just to confirm the ICV and ECU relay both work perfectly on my ABF Mk2. Any suggestions welcome as were are both at our whits ends at the moment and the deadline is looming. Thanks for looking
One other question we also have is that the car is now running using a 4 pin ECU relay number 32 from a MK2 golf but the guy build the wiring loom to take the 5 pin ECU relay number 30 from a mk3, would this make any difference?
NIghtroamer... a few ideas. RubJohnny has an IDLE calibration procedure in his documents that may be worth a look. Some digital vernier calipers and the document to set the gap. Also check the connectors, sensors and the grounds on the block while you are disconnecting. Our ABF idled high for a while, I also changed vac hoses (you may have a leak) and set the throttle gap and soon after it seemed to learn and dropped to 900. Our still hangs a little but nothing like it used to.. Its hard to hear leaks on our ABF as the ISV (I assume what you call the ICV) lets air in and you can hear it on ours with the pod air filter, its actually louder than the buzzing. So.. Set the base Throttle/IDLE gap Check connections and plugs Check the vac hoses Check for air leaks Wait for the GURUs to get into the nitty gritty. h
Hi buddy and thanks for your reply. So Set the base Throttle/IDLE gap - tried to find this guide but can't see it, has anyone got a link? Check connections and plugs- we have checked the plugs for all the sensors and all seem to buzz out/earth where they should. Check the vac hoses - we have replaced all of these to make sure there are no leaks. Check for air leaks again we have checked for all leaks we can think of, are there any places we may have missed? Thanks for your help.
Slight update sometimes the car sits at 2000rpm after you rev the engine other times it sits there bouncing from 1500 to 2000rpm. Still if I start it and do not rev the engine it will idle perfectly until I touch the throttle
Hi all Further quick update. Started the car this evening when cold using an ECU relay 30 (as fitted to the mk3) we know the Relay is faulty as it causes issues at 3-4k whilst driving. The car ran fine at idle and when opening the throttle the revs would drop down correctly. We then went back the the ECU relay 32 from my MK2 abf which runs fine through out the rev range and after a few seconds of opening the throttle the revs started to settle higher and higher. Next we went back to the ECU relay 30 as it did not present symptoms on first try and this time the revs started to settle higher and higher again. Interestingly we then found that moving the relay around seemed to change the idle, moving from idling at 1600ish rpm to bouncing from 1500 - 2000 rpm. then we would tilt the relay again ant it would stabilize at 1500ish rpm. what could be causing this issue? the relays 32 should work fine as it is all ok in my car. Could it be a bad earth or live feed? We are checking wires now.
As I said, the GURUs are probably on their way... So take my input as brainstorming rather than diagnostic. I have no idea about why the relays are so significant. When we first fired up ours, it too was bouncing around like that but from memory it was the vac line to the ECU. Theres a throttle body switch on the throttle housing that I would assume is part of the big picture of idle managment, but you've stated it idles correctly with a different relay so one has to assume it's not the switch. The ECU must be working or it wont spark, unless there's two circuits, Im almost certain without the vac line, the 1500-2000 issue occurs. Theres also a noticable system that delays the drop in idle when dropping below 2000 and the throttle body switch on, so it can idle. I think Toyotec and RubJohnny are the best to take the advice from as I still find myself scratching my head with all the systems and how they interoperate. I even went looking througn my saved documents in the hope of finding the throttle calibration document. It basically sets the air gap and idle switch position and I cant remember the gap needed. So maybe take a quick look at the switch on the throttle and see if its working while you wait. Sorry I cant be more helpful.
Thanks for the reply mate. We will have a new mk3 16v relay today and see if that fixes the issue. If not its starting to look like wiring. As we had the loom made by someone on the forums I would have to pick it apart sadly
the guide is in my sig you may have struggled to find it as its called 'g3abfidleswitch.pdf' rather than somethign more obvious Theres another one which covers matching the throttle body and isv to the ecu with vagcom 'abfbasicsetting.pdf'. this thread covers checking the idle switch function in vagcom also: http://www.clubgti.com/showthread.php?199583 the 30 and 32 relays should both work fine, the only difference is the 30 relay has an extra pin which allows the ecu to keep it switched on for a few seconds after the engine has switched off, this is why if you cycle the ignition on and off quickly the abf will only prime the pump once then wont do so again till ignition has been off for a bit. I've wired ABF looms with and without this extra feed and it makes no real difference to how the car actually runs. I find that ABF engiens are picky about the ISV, I tried several before I eventually foudn one it was happy with, but then again it could be the basic setting needed to be done in order for the ecu to be calibrated properly with the other isv, and i was just lucky with isv #3 if you pull the relay and jump the relay socket between where ecu relay pins 30 and 87 go with a decent bit of wire this will rule out the relay completely. if it runs better jumped go buy a new 30 relay from vw its around 15 edit: oh and check the isv is actually buzzing, some are pretty silent so you need to touch it to know. the main problem if it isnt is down to the wiring behind throttle body shorting out, the wire for the breather heater is on the same fuse as the isv (#15 on CE2 fusebox, CE1 you woudl need to check)
Hi RJ Thanks for your reply, sorry didn't see it on Tapatalk for some reason. So we have a new relay to test tonight hopfuly this will solve the issue as tilting the relay we had last night was affecting the idle, if not it may be the wiring near the relay somewhere! Odd though that it runs bad on my relay also which is all ok in my car.... ISV we have got working and My ISV both Buzz when on and we have checked their function is all ok on my car. As a test we squashed the ISV feed pipe down and the revs drop stable indicating maybe the ECU is receiving a bad signal from somewhere and trying to compensate. I will look through those docs now and see what we can find in a few hours when i get back to the car Thanks Again.
My ISV doesn't work on my 1994 ABF engine - I experimented and choked down the inlet pipe to it which tucks into a K&N set up - it may appearto be a bodge but it starts, idles and runs reliably - it has done some 1200 miles on track without issue - if you try this experiment it may get you to Devon (hopefully) I don't suggest its a fix and it may be a combination of things but in my case it works.
all of the ISV I tried did buzz just fine but only the 3rd one i tried actually worked with the engine, it may be isv can differ in the amount of air they flow at certain duty cycle as they age, or just manufacturing tolerances. if so swapping one from a running car may not be a good test? This was my theory anyway I couldnt believe I had so many bust ISVs but you never know apparently the allen screw in the end can be fiddled with to adjust them, but not sure if this is a good idea. they usually have a dab of yellow paint on it, if thats been disturbed this could be a clue someone has been at it before you
Ah interesting info thanks RJ. We have at lease 3 faulty (stuck) ISV so I may strip one to further understand their workings. We now have a new throttle body assembly on the was as we were not happy with the butterfly seating. Looks like someone has tried to clean the body before with a wire wheel or similar and when you apply small pressure the hunting stops :s
Hi all, well after another few sessions with the car, the dark and the rain it looks like we have a winner. The idle has now stabilised. We had tried a complete new throttle body and tested all sensors including checks found in the links above using VCDS. All the tests passed. Finally we got a spare ECU and coded it into the immob. This new ECU does not have any idle issues at all. so after much exploration we seems to have found a bad ECU to be the culprit. Big thanks to all for the input and help diagnosing this painful issue.
