I'm considering a gray-market car that has K-jet -- not KE or some other flavor, but straight K-jet with a CD ignition.
How reliable are these when they are setup correctly? Do they need constant fiddling to keep them running well? What sorts of things fail and how difficult is it to work on? It will be a daily driver (or whatever that means for me) probably 25 miles a week at most.
Was K-jet ever used with cats? If the car has cats and a BAR sticker does that mean the K-jet was converted or modified into something else?
opinions on Bosch K-Jetronic
-
mooseheadm5
- Posts: 23035
- Joined: Apr 08, 2009
- Location: Charlottesville, VA
- Contact:
All injected E21s were K-Jet. In the US, the 1.8s came with cats. Best thing to do is replace every piece of rubber in the intake and fuel system along with the lines from the fuel distributor to the injectors. The fuel distributor is a bitch as well, but there's a pretty good write up on rebuilding one based around the 928. General rule of thumb seems to be never to touch the fuel distributor.
Never had a reliability issue with that system on a well-maintained car though.
Never had a reliability issue with that system on a well-maintained car though.
Chris is right. Vacuum leaks are by far the biggest issue. Second, is the fact that many K-jet cars have had the fuel distributor settings tweaked due to vacuum leaks. If it is in good tune, then maintaining it shouldn't be too difficult.wkohler wrote:All injected E21s were K-Jet. In the US, the 1.8s came with cats. Best thing to do is replace every piece of rubber in the intake and fuel system along with the lines from the fuel distributor to the injectors. The fuel distributor is a bitch as well, but there's a pretty good write up on rebuilding one based around the 928. General rule of thumb seems to be never to touch the fuel distributor.
Never had a reliability issue with that system on a well-maintained car though.
There are some other parts that can be problematic like the warm up regulator. All in all, K-jet is a pretty reliable system. Most of its problems are created by people who don't know how to work on it. I would replace all of the boots and air lines you can and go from there. Is this an E21 or a Mercedes?
We probably had 90K on several E21s with K jet with minimal problems. A bad warm up regulator on one and I had to ever so slightly adjust the AFM on another one. Oh, I almost forgot, I had huge troubles on one for a while when a hose clamp was loose before the fuel pump. It didn't leak a drop, but was sucking air and since the whole thing works off fuel pressure it was a problem. But I found them to be very reliable.
As Chris mentioned, all 80+ US market E21s had it with a frequency valve, O2 feedback and a cat.
As Chris mentioned, all 80+ US market E21s had it with a frequency valve, O2 feedback and a cat.
Thanks guys. It sounds like the K-jet is reliable enough. This car is dealer maintained since new so I'm assuming it runs well and will pass smog.
I thought about that but right now I don't want to get into the polarizing issues about this model. At this point I'm trying to decide if I even want to go look at the car. It's not a BMW.mooseheadm5
It would help to know what car you are talking about.
-
mooseheadm5
- Posts: 23035
- Joined: Apr 08, 2009
- Location: Charlottesville, VA
- Contact:
K-jet is extremely reliable if one thing is true. The fuel system is super clean. Don't even think of starting a CIS car that has sat for 1 yr+ without at least emptying the gas tank and blowing out the fuel lines before the FD.
I spent a lot of time with K-Jet in my 1974 SAAB and my 1983 911. I still have the tools and got good enough that I can disassemble WURs and tune them by bending the bi-metallic strip and tap the plug back and forth the get the correct fuel pressures. I raced both cars in SCCA IT classes and loved to fiddle with it, along with my wideband.
The downside is that these systems are getting dang old and expensive when you need parts.
My SAAB had no emissions and no cat from the factory. My 911 had all of the goodies: cat, O2, frequency valve, AAV, Decel valve..
Here is probably the best resource online to understand CIS. The key is that you need to know what each part does, how it affects the rest of the system and how to test each part. Don't monkey with CIS until you understand it all. After you get it, it's pretty easy to diagnose and tune/repair.
http://jimsbasementworkshop.com/CIS/pag ... ction.html
I spent a lot of time with K-Jet in my 1974 SAAB and my 1983 911. I still have the tools and got good enough that I can disassemble WURs and tune them by bending the bi-metallic strip and tap the plug back and forth the get the correct fuel pressures. I raced both cars in SCCA IT classes and loved to fiddle with it, along with my wideband.
The downside is that these systems are getting dang old and expensive when you need parts.
My SAAB had no emissions and no cat from the factory. My 911 had all of the goodies: cat, O2, frequency valve, AAV, Decel valve..
Here is probably the best resource online to understand CIS. The key is that you need to know what each part does, how it affects the rest of the system and how to test each part. Don't monkey with CIS until you understand it all. After you get it, it's pretty easy to diagnose and tune/repair.
http://jimsbasementworkshop.com/CIS/pag ... ction.html
-
rollcentre
- Posts: 354
- Joined: Nov 30, 2012
- Location: Dallas tx
I had a CIS-e motronic car. I thought it was a pain and i really don't think i would own another car with CIS.... unless with it was a porsche 930.
Finally got mine running satisfactory after swapping in two different fuel distributors, new CIS injector/nozzles (very expensive) new fuel pumps etc. The fuel distributors are not exactly rebuildable, and i don't think they were availible new at all, so it was junkyard parts for me. I found one on VW vortex that I swapped in and it didnt work. I had to buy a used unmolested core on ebay and pay a mint for it. That one ended up working.
The slightest vacuum leak would have the car running like total shit. Didn't care for the extreme amount of fuel pressure required to make it work. keep a sharp eye on all of the fuel lines and fittings! and the aluminum and plated parts in the fuel distributor dont exactly agree with the ethanol fuel sold around here, so thats another strike against it.
I do remember the squeal of the injectors when fuel was being forced thru them. That was actually pretty neat.
Finally got mine running satisfactory after swapping in two different fuel distributors, new CIS injector/nozzles (very expensive) new fuel pumps etc. The fuel distributors are not exactly rebuildable, and i don't think they were availible new at all, so it was junkyard parts for me. I found one on VW vortex that I swapped in and it didnt work. I had to buy a used unmolested core on ebay and pay a mint for it. That one ended up working.
The slightest vacuum leak would have the car running like total shit. Didn't care for the extreme amount of fuel pressure required to make it work. keep a sharp eye on all of the fuel lines and fittings! and the aluminum and plated parts in the fuel distributor dont exactly agree with the ethanol fuel sold around here, so thats another strike against it.
I do remember the squeal of the injectors when fuel was being forced thru them. That was actually pretty neat.
Thanks for that link. The components of k-jet actually remind me of all the carburetor controls and smog equipment on my CS. My CS has thermo time valves, decel solenoid, cold enrichment based on water temp signal, etc.
I'm not sure I want to get into all that stuff. To make matters worse, the car I'm considering has two k-jet systems (hint for moose).
I'm not sure I want to get into all that stuff. To make matters worse, the car I'm considering has two k-jet systems (hint for moose).
wkohler wrote:That's the nicest thing I have ever seen Mike say about the E21.
Of course, that's also what he has said he hated about the E21z
Not quite. I think your thinking of a quote I've used that the worst thing about them is they seem to last forever. Reliablity isn't a bad thing, but underpowered, noisy, rust prone even in Cali with only moderate economy is. On the plus side, it's got a whole lot more room inside and in the trunk than my E36. 
Plus it's so crude it's about as bad as that 2012 Corolla I rented for vacation last year. 
-
mooseheadm5
- Posts: 23035
- Joined: Apr 08, 2009
- Location: Charlottesville, VA
- Contact:
I have a bunch of old Mercedes that run K jet (CIS) and KE jetronic systems. They are for the most part very reliable. The system has no computer.
The biggest issue that i've seen with CIS systems are caused from fuel sitting in the system and gumming it up which causes poor running.
Fuel distributors and warm up regulators can go bad and require rebuilding. Aside from the FD and the WUR, most parts are very cheap (Bosch OE fuel injectors are about $30, Bosch OE fuel pumps are $130).
You can pretty test and diagnose any injection issue on a CIS injected car with a fuel pressure gauge.
The biggest issue that i've seen with CIS systems are caused from fuel sitting in the system and gumming it up which causes poor running.
Fuel distributors and warm up regulators can go bad and require rebuilding. Aside from the FD and the WUR, most parts are very cheap (Bosch OE fuel injectors are about $30, Bosch OE fuel pumps are $130).
You can pretty test and diagnose any injection issue on a CIS injected car with a fuel pressure gauge.
Yes, that's what I learned over the last few months. Oldskool Ferrari mechanics like CIS because it is not much different from a carburetor in terms of diagnosis and adjustment. The mechanic who maintained this car for the last 22 years mentioned that it did not have the injector update done. Anyone know the details about that? He says that Bosch came out with an updated injector for the K-jet but he didnt have more details because he hasn't done that upgrade in a while.
new daily driver
new daily driver
Last edited by Devinder on Jan 30, 2014 9:02 PM, edited 2 times in total.
A friend who worked on these cars when they were new was telling me that they were never officially imported to the US so they all have soft valve seats.
If this is true, make sure you use a lead additive or else it's an expensive rebuild. The automatic transmission is a TH-400 so if that needs rebuilding, it's pretty cheap
If this is true, make sure you use a lead additive or else it's an expensive rebuild. The automatic transmission is a TH-400 so if that needs rebuilding, it's pretty cheap
True it was not made for the US market but It's an 84 model so valve seats are designed for unleaded. This model did have a 70s variant that probably needed lead.
5 speed manual with the heaviest clutch I've driven -- heavier than a big rig clutch
There are lot of familiar parts on it. The mirror switch is from an E28.
not only does it have TRX tires on it right now but it came with four additional new, never even mounted TRX tires. I'm in the market for Testarossa or 328 wheels if you guys know of any just collecting dust somewhere. Will trade for 9 TRX tires. Now that Daft Punk won a Grammy maybe I should keep it original.
I went through the records and found that only 6 items have been replaced since new:
1. one shock absorber (out of 6 total)
2. fuse box (factory update)
3. exhaust system
4. P/S belt
5. left fuel pump
6. battery
The hoses are original. I'm glad I have the 200 mile AAA card.
If you're thinking about getting one, dont wait. I've been following auctions and sales for about six years and this model hit bottom around the middle of 2013. The auction prices inched upward during the three months it took to get a PPI done.
5 speed manual with the heaviest clutch I've driven -- heavier than a big rig clutch
There are lot of familiar parts on it. The mirror switch is from an E28.
not only does it have TRX tires on it right now but it came with four additional new, never even mounted TRX tires. I'm in the market for Testarossa or 328 wheels if you guys know of any just collecting dust somewhere. Will trade for 9 TRX tires. Now that Daft Punk won a Grammy maybe I should keep it original.
I went through the records and found that only 6 items have been replaced since new:
1. one shock absorber (out of 6 total)
2. fuse box (factory update)
3. exhaust system
4. P/S belt
5. left fuel pump
6. battery
The hoses are original. I'm glad I have the 200 mile AAA card.
If you're thinking about getting one, dont wait. I've been following auctions and sales for about six years and this model hit bottom around the middle of 2013. The auction prices inched upward during the three months it took to get a PPI done.
Love the car but are you sure?Devinder wrote:True it was not made for the US market but It's an 84 model so valve seats are designed for unleaded
I'm not sure when Italy phased out leaded gas. In my country (the UK), unleaded became a requirement for new cars in 1993 and leaded was not phased out until 2000. There was very little forward planning and some cars built in 1992 had soft valve seats.
Dang; that is one sexy machine. Got more pics? Please?Devinder wrote:Yes, that's what I learned over the last few months. Oldskool Ferrari mechanics like CIS because it is not much different from a carburetor in terms of diagnosis and adjustment. The mechanic that maintained this car for the last 22 years mentioned that it did not have the injector update done. Anyone know the details about that? He says that Bosch came out with an updated injector for the K-jet but he didnt have more details because he hasn't done that upgrade in a while.
new daily driver