# 1.8 ABS mk3 golf engine injection system change?



## Bugsy_malone 666 (Dec 8, 2010)

ok so I have a mk3 golf with a 1.8 SPi engine, I wanted the manifold off the engine for another project engine I am building (manifold is same as the carb one) so I thought I would change the entire injection system for one off the 2litre GTi with a multipoint injection system as with individually controlled injectors i might be able to get better power/mpg and it would be more tunable.

So I bought engine wiring/ECU/MAF from a 95-6 golf (european model as Im in the uk) and the intake manifold I bought i didnt realise was from a 93, with injectors that all seem to be part of 1 unit rather than individual control. 

So i realise I need to change the injectors, or as all the injectors fire at the same time is there a way i could use the current 1.8 ABS wiring system? it only fires 1 injector, presumabley its the fuel pressure rating that will determin how much fuel goes in for the most part? I do have a set of injectors /fuel rail from a 1.8 mk2 GTi and they have individual plugs although similar are linked together being digifant.

Now this is where I was a bit unsure when it came to inlet manifold. the 1.8ABS manifold is like the carb one, so it has water running through it to stop 'carb icing' even on the injection system one! so next to one of the inlet ports there is a water outlet on the head, the GTi manifold doesnt have this and also apparently has different shape ports, I wondered are the 1.8/2l heads that different? or on the 2litre is the water hole just plugged with a core plug?

now otherwise I have been thinking if head/manifolds wont match then I need to look at an alternative as I need the 1.8 manifold for something else. I do have a 16v head knocking about of a KR 1.8, I have the inlet manifold for that but its mechanical injection, will the 2litre GTi ecu/wiring run the 16v head alright?

I am at the stage where realistically I dont want to buy more than 1 or 2 components that are relatively cheap.

Any ideas?


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## ps2375 (Aug 13, 2003)

You are not going to get this done with 1 or 2 more components. It sounds like you need to read up on engine management systems, to truly understand what you are asking about and how to make the switch. I doubt the 2ltr system will run the 1.8l motor as the 2.0l motor has a crank sensor and the 1.8 does not, one very basic diff.


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## Bugsy_malone 666 (Dec 8, 2010)

I think what I meant by 1 or 2 components was on top of what I already have, I have the most part of the injection setup, but I am trying to find out the missing links and trying to fathom where I failed on parts collection

I think it can depend model to model on what actually triggers the injection system as the early mk3 had a digifant system which appears to run the same as the mk2 golf practically. That was fired from the distributor

I guess what I was trying to assess is from a 1996 car what problems I might encounter from using a the injection system on an earlier engine, ignoring the fact one is 1.8 and one is 2litre as that can be sorted out by having a tuning session to get the fuel maps adjusted once done.

I understand there are a few differences but I guess its down to the year to year differances that I am interested in finding out about, I thing to be honest I guessed a little bit too much when doing some purchases (as I found with my inlet manifold not realising the head on the 2litre has injector cutouts on the edge of the manifold).

currently the 1.8 is a single port injection system, I did to some extent wonder how thew single power 'carb' matched up against a multipoint injection system. IT provides as much power as the digifant 2 GTi mk2 golfs.

I bought fairly cheap a complete ECU and wiring loom from a 96 mk3 golf, along with an airflow sensor for the same, what I didnt purchase was the right inlet manifold, I bought a digifant 2E manifold which fires the injectors as a set rather and sequentially.

So after a bit of learning I have been thinking that I may need to investigate getting a Digifant ECU from a 2E as I think they run off the distributor hall effect sensor, then I would need to change a few pins on the ECU multiplug?

or are they different?

I am looking to use what I currently have to build a multipoint system thats more efficient than the stock SPi with a bit more power to go along with it.

Although today I did just think why do I bother! but the cars hit pretty much its lowest value, so its fairly good for playing with as I have another daily!


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## B4S (Apr 16, 2003)

If the 1.8 SPI is the same as the one we got here in Canada (I believe it is), then the head will not have injector ports. The 2E manifold has the injectors in it, but the ports are ovaled out for the injectors. As well, the 1.8 is based on a Motronic ECU, and not Digi, so the wiring will be completely different. Swap the harness.

You may need to swap the heads to accomplish this. As for the other questions, our 2.0s ran on Motronic 2.9, not Digi, so there is going to be a lack of info about that over here .


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