Changing fuel injectors on 400i

These injectors are just pressed-fit in the cylinder head, you can easily pull them by hand. If the o-rings are dry, this may require some persuasion. That's roughly a one hour "easy" job.

I bought some injectors on ebay ($100 per pack of 6). You can search "BOSCH X6 pcs Injector Fits MERCEDES FERRARI PUCH RENAULT 190 Targa GTS 113975".

 

Anthony
Similarly, I bought a new set of 12 on eBay for a reasonable price. I bought 12 new o-ring from F-dealer. After removing the injectors I tested one or two new ones using 40 or 60 psi air pressure with carb cleaner in the fuel inlet. New injectors gave a nice full cone spray pattern. I tested each of the old injectors. I few gave a near cone pattern, others a limp stream. New injectors were in the car and idle was smoother and generally more drive able. I put all the old injectors in a car with the tips submersed in carb cleaner. Over the next days or maybe a week or so, each of the injectors gave a nice full cone spray just like the new ones. Once they were all good, I have them stored and I plan to use them some time just as if they were new!

So if you don't find new injectors are a reasonable price you can "reclaim" your old ones. There is nothing that can go wrong with the injectors except various deposits that ruin the spray pattern. Be sure to use new o-rings in any case. If you find new ones at a good price, do what I did and you'll have a spare set.

Another lesson learned, these injectors do foul, so use a good Fuel Injector Cleaner at least once per year.
Ken

 

Mercedessource has lots of great information on this -

I ended up buying one of there testers which makes cleaning and testing the injectors very simple.
Testing they all have similar opening pressure and making sure none of them weep makes warm engine starting much easier.

I also made myself a tool for pulling the injectors
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I must say I was not so lucky with O-rings bought on ebay. BOSCH Rubber Seal O-Ring (ref 1280210711) DO NOT fit... No way my local Ferrari dealer (Ford dealer actually) can source these for me.

 

On 928 classic (see archive here https://www.ferrarichat.com/forum/attachments/porsche-928-bosch-k-jet-cis-baseline-fuel-tuning-procedure-pdf.3138369/) there is a good article on the subject. Abstract:

Cycle-flush
This procedure cycles fuel and cleaning agent through the CIS and fuel systems. The entire system is a closed-loop, from fuel delivery (thru CIS) to fuel return (to tank). Add 8 ounces (½ can) of B12 to the fuel tank (preferably before adding fuel). Ignition switch position OFF. (remove metering safety connector). Continue cycle-flush for 15 to 30 minutes. You should be able to hear fuel returning to the tank. For best results, repeat this process 2 or 3 times, once per day.

Important: If you hear a very unique squealing sound coming from the engine bay, STOP CYCLE-FLUSH IMMEDIATELY.

Note: I'm impressed with the results of this procedure. It's a great method, especially if performed before first starting a non-runner.​

That's an easy way to revive injectors. Note however that in the long run injectors do wear, so one old injector may spray more than others, in this case either you adjust the flow of each individual injector (our alloy metering units do allow for such adjustment unlike cast iron units), or you just use new injectors. My car was adjusted in such a way, but rapidly after the adjustment was off again.

 

If you do not have B12, here is the recipe to make your own :
- 0.1 litres of synthetic thinner
- 0.2 litres of WD40
- 0.2 litres of isopropyl alcool
- 0.5 litres of kerosene (jet fuel is hard to find, the liquid used for portable heaters can do).

This is to be mixed with 25 litres of gasoline

I must say however that I do not use these cleaners anymore: our gasoline does contain so much ethanol that everything is (deadly) clean now...

 

Al, What solvent does he use for cleaning? A Home Depot can of Paint Thinner showed up in the background of video after he did cleaning off line. Also, which kit did you buy. This clearly is more accurate than what I did!
Ken

 

Hi Ken,

I purchased this tester about 6 years ago and it came with access to more online information (prices were in US$) -

CIS Gas Fuel Injector Spray Pattern Tester and Nozzle Cleaner
Works on all models from 1977 to 1993 with the Bosch C.I.S Fuel Injection system - see models listed below
(GEG-CISITESTER)

GEG-CISITESTER

$162.50

CIS Gas Fuel Injector Removal, Cleaning and Testing - On Demand Video Manual
How to know for sure how well your gas fuel injectors are performing (1976 to 1993 CIS ONLY)
(VM-CISI)

VM-CISI

$0.00

Bosch C.I.S Injector Testing Procedures by Kent Bergsma - Download
(INS-PDF-CISTEST)

INS-PDF-CISTEST

$0.00

This is the link to the latest version of the tester -
https://mercedessource.com/store/cis-gas-fuel-injector-spray-pattern-tester-and-nozzle-cleaner

The main cleaning agent was just thinners which worked well on my injectors.

Cheers Al

 

Any diesel shop can test and clean your injectors inexpensively but I find a lot dont pass the test 40 years later in that the springs become weak. I replace them with brass ones and carry on.

 

Based on what I have read here, I will not use my "spare", cleaned injectors without testing them first.
Ken

 

My tester is the distributor itself: you can just pull all the injectors, place them in small transparent bottles (the polyamid tubing do allow for some reasonable flexibility), turn the enrichment screw a full clockwise turn (or remove the rubber conveyor and pull the airflow sensor disc) and see the spay pattern. If it's a nice cone they are fine, otherwise bit the bullet for the "new" injector types.

The injectors I can source do not have the same colour as what they used to be, I do not know if this is what @Newman means? Maybe the original injectors were better, but as said no possibility to compare as my old ones were really bad. As far as the colour is concerned, my car does not have the market value of a Daytona I don't think it's worth searching for NOS injectors for this sole reason
.

 

Long ago, the K-Jet/KE-Jet injector was Bosch 0437502010 which has a plated steel body and looked grayish/silver (but tended to get rusty with use/time).

The latest available K-Jet/KE-Jet injector is Bosch 0437502047 which has a brass body (still gets oxidized some with time/use so doesn't look as pretty, but doesn't get as gnarly as the original steel ones). AFAIK, the working bits inside are still the same, or would be same as they would be if the body was still steel. IMO, what's changed is the steel ones used to be the flagship injector built in Bosch's best (German?) factories -- today, they've moved to low-cost factories (and could be using lower cost materials, too).

 

The WUR were made in a French factory, not sure about the other components. This being said, the made in Serbia TRX are much better than the dry rotten tire that sits in the bottom of my trunk. I am glad Michelin and Bosh do still produce these parts, wherever their factory might be.

 

Me, too! (Wasn't complaining, just making an observation about how products evolve.) I think a lot depends on the market where the Bosch parts are sold -- here in the US, many Bosch replacement parts are "made in Mexico", but would guess that Bosch has factories in the far-East and probably Eastern Europe now, too, to serve those markets.

 

Speaking of tires, I weigh tires and other parts just to know. The original France XWX tires had a very thick bead on them and the rim has a corresponding large bead channel to accommodate that design. The new tires are about half as thick in the bead which is fine and weigh a whopping 7 lbs less than the tire they replace. Thats a big deal. 7 lbs less unsprung weight on each corner. I dont have an original or early TRX to weigh but I expect a similar finding.

 

I'm sure my 16" wheels and Goodyears are far lighter than TRX and metric wheels.

 

Maybe not. If the wheels on your car are repop QV rims they're a lot heavier than real QV rims, Ive had both on 308's I used to own.

 

The trx rim could still be heavier as they are almost half an inch larger in diameter. Could also be lighter though as they do not require a spacer and are made out of a lighter alloy,

As far as the tires, the new ones do look better. Our tires used to be made by the factory newbies (one of my mechanic worked there a few decades ago). Working on the TRX was how they were training them. The workers in the Serbian factory are not less skilled than their French counterparts, and their tools are much better. The moulds for instance have been updated.

The coumpound is also very different, and I've seen that the classic line now includes hard/soft rubber, whereas you could only have "medium" a few years ago (the TB tires are now available in TB5 and TB15).

I would be tempted to consider that the bean-counter have made all possible effort so has to reduce the amount of material when updating both the moulds and the rubber...

Will put my 2004 spare wheel on the scale!

 

I'll weigh my spare wheel/tire vs. one of the 16" wheel/tires this winter during my R&R.
It probably is about time that I buy the 5th 16" wheel. That old TRX may not be a good 'get me home' spare.
Ken