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need more information.
1.8 16v, 2.0 16v I think they are diff and you would need to swap entire harness.
I could see it dumping more fuel but you could do that with a potentiometer . read the diy on how.
just swapping the ecu wont work...
 

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12 Golf 2.5, 99.5 Cabrio GLS
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The old CIS cars came in a few different forms. Let's look at the differences...
GX engine code- used on 85-87 Jetta, Golf (85hp)
smaller valves in head
single (toilet bowl) downpipe
no knock sensing system (vacuum timing advnace)
single wire oxs
8.5:1 compression
HT/RD engine code- used on 85-87 GLI and GTI 8v (100 or 102hp)
bigger valves
dual downpipe manifold
knock sensor, more radical timing advance
more advanced computer (CIS-E with DPR for more dynamic fuel control, though some GX engines came with this)
10:1 compression
(* the HT engine was use din 85, and the RD was used in 86-87. On the HT there is a wire on the ECU that connects to another pin on the ECU... supposedly if you cut it the timing map changes to match the RD code and you gain 2hp...)
A head and downpipe swap will get you much more power off the bat. But the compression won't change... the compression is low to prevent ping. if you had more you'd need the knock sensor system to compensate for increased ping/knock.
There was also another engine, the MZ. It was in Canada only. They were identical to the GX 9small valves and all) but they deleted the oxygen sensor and computer (it was pure mechanical CIS). THis engine made 90hp.
In short... there are several computers (knock control, oxygen, and ignition controller which really isn't a computer but still...). The GX shouldn't have a knock system, and the oxygen sensor computer is what controls fuel. Only some GX engines had CS-E (the majority of GX engines had a completely different computer that won't swap with the GLI one). The ones that DID have CIS-E, I guess you could swap them and it might provide a theoretical advantage but I don't see much...


Modified by VDub2625 at 1:59 PM 3-20-2010
 

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Discussion Starter · #6 ·
my hopes were that this would enrich the fuel delivery process. adding a g-grind cam and a dual down pipe with a ported jh head as well. has anyone ever heard of someone doing this with the computer. thanks for the advice so far guys. much appreciated.
 

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12 Golf 2.5, 99.5 Cabrio GLS
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You could turn up the fuelling a tiny bit at the fuel distributor.
Is your fuel distributor black or aluminum colored? Does it have a gray or black box on the engine side with an electricl connector on it or is there nothing there?
 

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12 Golf 2.5, 99.5 Cabrio GLS
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That's a good idea but it only works if you already have CIS-E (it uses the WOT switch, which is CIS-E only, to trigger a "cold" signal to the ECU from the coolant temp sensor, both of which are only with CIS-E). GX engines could come with either.
ETKA lists one single ECu for GX and HT engines for 1985... for 86 and 87 they do show different part numbers but i somehow doubt one is programmed with any more fuel.
 
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