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Discussion Starter · #1 ·
Hi I've recently acquired a 1997 Golf GTI 2.0 AGG 8V. The engine had a head gasket blown when I first got the car, so I replaced the gasket & had the head skimmed. Also I changed piston rings,honed the cylinder bores, changed big end bearings valve stem oil seals & ground in the valves.
The issue that I'm having is the engine seems to be over fueling, 00537 lambda sensor at upper limits is a permanent fault code & the idle is erratic & sometimes holds back when at around 3000rpm.
I've changed the o2 sensor, checked timing, all engine breathers have been changed plus coolant temp sensor.
Any help or this issue would be very much appreciated.
 

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Which diagnostic system do you have? With the engine running, disconnect the fuel pressure regulator vacuum line but take care as fuel my spray out.
 

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Discussion Starter · #3 ·
I've been using an old version of Vcds which was not much help to be honest.
I've also used the wow system from Wurth.
I pulled the pipe of the fuel regulator & the idle was much better. No fuel leaking.
The previous owner has said he replaced the regulator I've removed & inspected it & all looks good.
 

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Discussion Starter · #5 ·
I can't say for certain but I think its 3 bar.
I won't be near the car until Tomorrow I can find out for definite then.
Whats your thoughts? The regulator not allowing enough fuel pressure?
 

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The lambda sensor is detecting too much fuel which I have had with these regulators which were not designed for the E5 fuel we are being forced to use which will soon be E10... better carry a fire extinguisher. Without looking at the VW manual at work, I can’t remember the functions available with this Simos ECU so prod me tomorrow. If I remember correctly, basic settings 099 turns off the the lambda control without unplugging anything. I don’t get my hands on many ADY and AGG engines these days (although I use a their pistons in a special conversion) but common issues in their heyday was coolant temp sender and ECU relay failure.
 

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Discussion Starter · #7 ·
Hi no luck with any markings on the fuel pressure regulator.
I'm going to test my fuel pressure hopefully tomorrow when I get a suitable gauge.
Where's best to tap into on the fuel system the delivery side or the return?
 

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That will cause the engine to over fuel and the Lambda sensor will send a rich signal to the ECU which will reduce the injector duration until it can get it back to where the mapping is for a 3 Bar Bosch 0 280 160 557 (VW 037 133 035 C) and it may run out of the window of correction which is 20% but a rich error will be triggered at 10% ALTHOUGH 0.5Bar is not much and an odd figure as most "uprated" regulators are 4 Bar. Certainly I would go back to a standard 3 Bar.
 

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The lambda sensor is detecting too much fuel which I have had with these regulators which were not designed for the E5 fuel we are being forced to use which will soon be E10... better carry a fire extinguisher. Without looking at the VW manual at work, I can't remember the functions available with this Simos ECU so prod me tomorrow. If I remember correctly, basic settings 099 turns off the the lambda control without unplugging anything. I don't get my hands on many ADY and AGG engines these days (although I use a their pistons in a special conversion) but common issues in their heyday was coolant temp sender and ECU relay failure.
I have a 1999 Golf Convertible with a 2.0 8v AGG lump. I have exactly the same issues as the OP, high fuel consumption and 00537 lambda sensor at upper limits code.

Ive changed plugs, bosch leads, genuine vw temp sensor, fpr for another 3.0 bar item I had spare, distributor cap and arm for the right sagem nos parts and it runs better but still over fuels. Is that all down to e5/e10? I was thinking perhaps an injector is clogged or sticky? Found a recon set for £85 - The car only has 62k on it though so I'm not convinced.. I can't get an MOT on it, as the CO is too high.. been tempted to just convert the engine honestly, but I'd like to keep it original if possible.
 

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Which diagnostic system do you have and do you have access to a Co meter or 4 gas?
Full VCDS hex v1 - no sadly no access to a co meter.. a friend has a gunson gas tester but I have heard they are hit and miss. I'm open to buying any tools to help. Someone suggested testing the fuel pressure?
 

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The Gunson tester may help, you just need to know the Co although the Lambda would help which requires a 4 gas. With the engine idling, go into Basic Settings 04 and enter group 099, this turns off the lambda correction and the Co should be approx 0.7% or Lambda 1
 

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Discussion Starter · #14 ·
Hi the cause of my code & subsequent overfuelling issue was the wrong exhaust manifold gasket fitted this allowing unmetered air close to where the oxygen sensor is situated & fooling the sensor into thinking the mixture was lean & it in turn opened the injectors for longer to compensate.
From memory the injector duration was 4.7 ms instead of around 2.5ms.
The exhaust manifold gasket that was supplied in the gasket set was metal & in one piece, it should have been 4 individual gaskets.
I hope this info is of use to you.
 

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That is where I was heading but more the 3 bolt flange gasket. The first time I had that was in the very early 90’s when I put a Golf Rallye G60 engine in a Golf 2 and these had no diagnostics. The gasket was a genuine metal layer shim part and is was allowing a tiny amount of air to be drawn in straight at the lambda sensor.
 
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