Cold Start Fuel Line, Is this really needed? Options

[edmitch]

Sorry if this a known thread - I didn't find one.

Converting my injector rails to new design by Injector Rehab - really like it but there is not a fuel line connection for the cold start - my existing tube set has a take off line between 1&2 cylinders.

Is this really important? I live in the south and the car is garage kept - normally nothing below 50 degrees Fahrenheit

https://injector-rehab.com/product/complete...ctors-included/[/img]


Thanks for any help

FYI - picture leads to VW set - they make the same for Type 4 Porsche - sorry for error but should give you the concept.

[edmitch]

Without any insights and brilliance from the collective gurus here- I'm thinking I'll just run a t off of the fuel line - can anyone say "Doh"?

[mate914]

Without any insights and brilliance from the collective gurus here- I'm thinking I'll just run a t off of the fuel line - can anyone say "Doh"?

Why not ask the company you bought product from. Most likely no one on 914world has used that kit.

Matt

[JeffBowlsby]

At 50F ambient, the thermoswitch will not trigger and the CSV will not fire. The thermoswitch only triggers at temps below freezing, depending on the temp rating of the switch.

Ok to remove the CSV, its fuel line and the thermoswitch. Keep the AAV. If you remove the CSV from the air plenum you will need a block off plate and gasket.

[StarBear]

IIRC, the cold start is for near/sub freezing temps. Probably not needed in SC in any but extreme situations. At least for the 1.8s. Presume also for the 2.0s.
Ok to correct me if I’m wrong.

[StarBear]

IIRC, the cold start is for near/sub freezing temps. Probably not needed in SC in any but extreme situations. At least for the 1.8s. Presume also for the 2.0s.
Ok to correct me if I’m wrong.

Ahhh… Mr. B beat me to the punch while I was typing.

[emerygt350]

Do let us know how it goes if you remove it.

[edmitch]

Thanks for the insights on how this thing works - agree with all inputs.
It always helps me to air this stuff out. (as I try real hard not to break things ;-))

[wonkipop]

IIRC, the cold start is for near/sub freezing temps. Probably not needed in SC in any but extreme situations. At least for the 1.8s. Presume also for the 2.0s.
Ok to correct me if I’m wrong.

bit higher than that for L jet.
Cold Start Injector does not open above 59 deg F (15 deg C).

below that temp the thermo time switch will control the amount of time the cold start injector opens. up to a maximum time. thats the bit i can't recall off the top of my head. either 3 or 10 seconds.

don't know what the case is for D jet. probably completely different.

OP does not say what system he is running.

i know mine for a fact def operates in standard winter conditions here which are not near freezing and are in the 5-15 deg C atmopsheric temp zone. when we recommissioned the car the first few times we tried to fire it up it ran for about 5 seconds. off the cold start valve. we discovered the main fuel injectors were blocked and kaput despite being cleaned and tested. so it definitely fires in an L jet at temps well above freezing.

not quite sure how you would do it. T off the rail. at least in an L jet.
the cold start injector fitting on the end forms the T in the L jet as the flexible fuel lines run into either side of the CS injector. i've never had it apart or off to look closely at that fitting.

[wonkipop]

Sorry if this a known thread - I didn't find one.

Converting my injector rails to new design by Injector Rehab - really like it but there is not a fuel line connection for the cold start - my existing tube set has a take off line between 1&2 cylinders.

Is this really important? I live in the south and the car is garage kept - normally nothing below 50 degrees Fahrenheit

https://injector-rehab.com/product/complete...ctors-included/[/img]


Thanks for any help

FYI - picture leads to VW set - they make the same for Type 4 Porsche - sorry for error but should give you the concept.

i just had a look at that link.
nice designed set up.
i don't see where you have a problem duplicating the standard set up, whether for L jet or D jet.
those fuel rails simply replace the originals which are also two separate rigid rails (in part).
you join both rails with flexible high pressure fuel hose. with the CS injector - at least in L jet you simply duplicate what was there. line joining left and right banks is two part.
comes into cold start injector on one side and out the other side to the other fuel injector rail. line up from fuel pump goes into right hand side. line out from left hand side goes to fuel pressure regulator and from there back to fuel pump T and ultimately tank return.

EDIT
i see reading fine print on the linked website it is for 74/75 1.8.
so it is L jet you have.

if i was you i would keep the CSI in. if nothing wrong with it and its operating fine along with its thermo switch. all you are replacing with this set up is the original sections of metal tube fuel rail either side which have a hose to the injector. thats what these bits do. the rest of your fuel line plumbing just duplicates the factory set up. hose comes out of right hand bank goes into right hand side of cold start injector. leaves left hand side of colds start injector and goes to left hand injector rail.

[Van B]

At 50F ambient, the thermoswitch will not trigger and the CSV will not fire. The thermoswitch only triggers at temps below freezing, depending on the temp rating of the switch.

Ok to remove the CSV, its fuel line and the thermoswitch. Keep the AAV. If you remove the CSV from the air plenum you will need a block off plate and gasket.

CSV operates above freezing. Only runs during cranking for normal colds starts and only runs after cranking based on input from the TTS. I’ve tested it myself.

[JeffBowlsby]

My comment on the trigger range of the 914 CSV thermoswitches is backed by various factory manuals summarized on Anders page, "Troublehooting Table" found here: https://members.rennlist.com/pbanders/DJetParts.htm. If ambient air temps are above these the CSV is not designed to fire.

311 906 161 : -12 to -18 deg. C / 10 to 0 deg. F
311 906 161 A : 0 to -10 deg. C / 32 to 14 deg. F
311 906 161 B : -2 to -8 deg. C / 28 to 18 deg. F
311 906 161 C : -6 to -14 deg. C / 21 to 7 deg. F

[gord]

I did this conversion earlier this year and disconnected the CSV. I left the actual valve in place, but disconnected and capped off the fuel line. I later discovered that my AAR had also gone bad, which I still need to fix — In the meantime, I just disconnected and capped it off too (which means the car now needs to be warmed up for a 3-4 mins before it will idle properly).

Here's the post about my Injector Rehab installation:
http://www.914world.com/bbs2/index.php?s=&...t&p=3140437

[wonkipop]

My comment on the trigger range of the 914 CSV thermoswitches is backed by various factory manuals summarized on Anders page, "Troublehooting Table" found here: https://members.rennlist.com/pbanders/DJetParts.htm. If ambient air temps are above these the CSV is not designed to fire.

311 906 161 : -12 to -18 deg. C / 10 to 0 deg. F
311 906 161 A : 0 to -10 deg. C / 32 to 14 deg. F
311 906 161 B : -2 to -8 deg. C / 28 to 18 deg. F
311 906 161 C : -6 to -14 deg. C / 21 to 7 deg. F

they are all thermoswitches for Djets jeff.
temp switch for an L jet is 022 906 163 for 74 and 043 906 163 for 75.

OP must have a 1.8 as the injector rail system he is interested in and is proposing to use is for a 74 75 1.8. they do not appear to be advertising a system for the D jet cars when you look into the website link.

@Van B is definitely correct. he is talking about L jets.
we have all been through the exercise with our L jets a few years back.
the temp sensor and the cold start valve operation is a whole different kettle of fish.
and similarly i have observed mine firing and can assure you its well above those temps quoted for the D jets.

also i do recall when we were all going into this a few years back when Van was going right through his system we came across info that indicated the L jet 912E cold start valve operated to even higher ambient temps before it was cur off by the temp sensor.
it was something like 90F from memory. quite high.
the 59F or 15C figure i have quoted is direct from the factory workshop manual for the 914 L jets. i also have VW L jet manuals for the 412 which quote the same/similar figure of 15C/60F.

if i was the OP and i was putting the fuel rail system he proposes in i would be leaving the CSV in. L jets from the factory had a weak cold start idle from the day they were made. suspect they do not have the same strong enrichment settings built in to the ECU as D jets had. CSV has a role in getting the engine started easily.

[GregAmy]

I did that on my D-Jet before converting to Microsquirt. Given I rarely drive the car below 40F it was never an issue.

Per OP's sig it's a 2L, thus D-Jet.

[JeffBowlsby]

he is talking about L jets.

AHA! Thanks for pointing that out, it was not clear...all I saw was the 74 2.0L in his sig.

[ClayPerrine]

Simple fix:

Install a metal T fitting in the middle of the rubber line that runs across the front of the motor and connect it to the cold start injector.

[dr914@autoatlanta.com]

2.0, 1.7 40 degrees and colder, 1.8 60 degrees and colder

Sorry if this a known thread - I didn't find one.

Converting my injector rails to new design by Injector Rehab - really like it but there is not a fuel line connection for the cold start - my existing tube set has a take off line between 1&2 cylinders.

Is this really important? I live in the south and the car is garage kept - normally nothing below 50 degrees Fahrenheit

https://injector-rehab.com/product/complete...ctors-included/[/img]


Thanks for any help

FYI - picture leads to VW set - they make the same for Type 4 Porsche - sorry for error but should give you the concept.

[wonkipop]

2.0, 1.7 40 degrees and colder, 1.8 60 degrees and colder

Sorry if this a known thread - I didn't find one.

Converting my injector rails to new design by Injector Rehab - really like it but there is not a fuel line connection for the cold start - my existing tube set has a take off line between 1&2 cylinders.

Is this really important? I live in the south and the car is garage kept - normally nothing below 50 degrees Fahrenheit

https://injector-rehab.com/product/complete...ctors-included/[/img]


Thanks for any help

FYI - picture leads to VW set - they make the same for Type 4 Porsche - sorry for error but should give you the concept.

thanks for confirming that doc.
(IMG:style_emoticons/default/beerchug.gif)

[wonkipop]

he is talking about L jets.

AHA! Thanks for pointing that out, it was not clear...all I saw was the 74 2.0L in his sig.

maybe he has got a 2.0
it has not been entirely clear.
but the link to the retail website is interesting as it states the kits for 914s are fir 74 75 1.8s.

anyways. i think you could delete CSV on a D jet as some have stated here.
but i think its a different matter for an L jet.