Cold Start Or Hot Start - on my 1983 1.8 Gti

 Hi all,

1983 Gti owner and this i my first post on here.

Hoping someone can help!

My car has a cold start issue & always has since i bought it in August 2019. It would trun over but run lumpy for about 30secs or cutout if i tried to apply any revs. Then would run perfectly fine.

I bought a new/2nd hand 5th injector put it on and it started prefectly from cold, which was great, easy fix…or so i thought…. My cold start issue had then turned into a hot start issue! It woud start first time and run great from cold, however when hot if i turned the ignition off it would not start again unless i left it for about 15mins or so. Another sympton which only appears when using the new 5th injector was that it would start to misfire/splutter under acceleration after 8-10miles.

I have swapped back to my original 5th injector as i thought it was better to have a cold start issue than a hot start/misfire. Quite embarrassing when on the petrol station forecourt!

Has anyone any thoughts on what this could be? or how i might solve this problem?

Thanks in adavance - Martin




 

Welcome!! 

Warm up regulator could be a good starting point for both cold and hot starts.

Re the hot start, the fuel pump loses pressure and it won't start. lhasadreams always recommends a pressure check to ensure everything is in fine fettle too. 

Hey Martin,

I was also going to make my first post but I just came across yours.

I'll be keeping an eye on this thread as I have a very similar issue with my 1980 MK1 1.6 GLI which I've just had a couple of weeks now.

Cold starts are always fine but hot starts (after say 20 minutes of engine off) can be really tricky, so much so that at times, bump starting has been the only way to get it going.

And interestingly, I'm also getting that funny lumpy, splutter thing but only when the engine is hot, after 10 minutes of driving maybe.

Would love to hear if you have any luck as your problem sounds very similar to mine!

Phin

Thanks for the reply Dano!

The warm up regulator was one of my suspects.

I have seen you can get rebuild kits for the WUR i may attempt it some point soon….

Have you attempted anything to fix the problem SpruceGoose ?

I have tried a new fuel pump and a fuel filter so far. (before i posted on here). Didnt make any difference.

I had a little run out on friday and the misfire/splutter when warm happened even with the origianl 5th injector on. So i think that rules out the 5th injector swap causing the splutter at least.

I just find it strange that the hot start doesn't happen with both 5th injectors.

You'll need a pressure guage to enable proper testing of the K-jet system, and getting the 'hot' and 'cold' pressures set correct on the WUR.
WUR rebuilds are quite easy - I think I got my kit from a chap on ebay (missing.parts) based in Germany - very helpful, very good instructions.
Have a google for Mr K-Jet - based in Oz, but he's got some decent guides on setting hot and cold pressures.
Poor hot starts can be caused by a failure of the fuel accumulator (located near the fuel pump). A hot engine will cause the fuel in the lines to evaporate, the accumulator holds the lines under pressure for about 20 mins or so to prevent this happening.
k-jet can seem very complicated but it's not that bad. You just need to read a lot about it, consult various sources, and you'll soon have a good idea of how it works and how the different components overlap. Haynes manual is a good place to start.
There is a facebook group called Bosch CIS Wizards - there is some good info on there, but you'll absolutely need a pressure guage to do anything right.

Here are some guides to get you started:

The forum has a guide on the fuel system:
https://vwgolfmk1.org.uk/index.php?page=cedi&type=misc&id=27

Haynes Manual
Chapter 4 Part B:
Fuel and exhaust systems -
K-Jetronic fuel injection - 8 valve engines

It explains how the KJet system works & how to carry out tests on the individual parts, Warm Up Regulator, Cold Start Valve, Thermo Time Switch, Auxiliary Air Valve.

Cabby info
- has links to some good PDFs
https://cabby-info.com/files/fuel/KJetronicManual.pdf


Essential youtube channels/vids tutorials on KJet Fuel System:

@GreyGooseRestorations - has an excellent playlist on the KJet system, albeit targeting MK2, extensively explaining each KJet part
Bosch K-jetronic - Mk2 Golf GTi 16v - Deceleration Cut Off Valve - YouTube

Cold Start System:
Bosch K-Jetronic - Mk2 Golf GTi 16v - Cold Start System - YouTube

WUR issues:
K-jetronic - Warm up Regulator Failure - YouTube



@ShinyFastLoud - has a few vids on how to test the system pressure & rebuild WUR, what fuel pressure test kit is needed
Mk1 VW Bosch CIS Fuel Pressure Test - YouTube

@stevenharpervw - a good video on how to check injectors, and a neat way of triggering the fuel pump from the engine bay
Removing, cleaning and testing CIS injector flow on a vw Mk1 golf gti - YouTube

@OlisGarage - an excellent video here on how to set the timing
VW Mk1 Mk2 & Citi Golf Static Ignition Timing - NO Timing Light Needed! - YouTube

@jva8291 - a HALL SENDER bench test
Testing c900 Hall Sensor - YouTube

@pentagrammotorsport - Steve Matthews, Pentegram Motor Sport - a few multi meter checks for ignition testing
Mk1 Golf Ignition Testing - YouTube

Bosch K-Jetronic (CIS) explained
Bosch K-Jetronic (CIS) explained - YouTube

Other vehicles using the KJet system:

@garageofdad - goes through the entire KJet problems from set up on Audi 2.2
Audi Coupe 2.2 - YouTube

@Mercedessource - explains KJet on Mercs
Bosch K-Jetronic Fuel Injection: Diagnose BEFORE Buying Parts - YouTube

@JoeEngineer - Porche 911
How To Test Fuel Pressures for Porsche 911 Bosch CIS K-Jetronic Fuel Injection - YouTube

@RestorationApprentice - Porsche 924 - WUR & Metering head rebuilds
1985 Porsche 924 NA full Restoration - YouTube

@eliotmansfield - Delorean
Delorean k-jetronic fuel warmup regulator test - YouTube

https://www.ebay.co.uk/itm/297067869805?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338590836&toolid=10044&customid=c07b1a9df3901a0073b27d711c34dcb7&gclid=c07b1a9df3901a0073b27d711c34dcb7

This is a brilliant book but so expensive now.