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Thu Jun 19, 2008 7:44 pm

Just picked up a 89 16v gti the car bucked bad in 1st,and 2nd.Found out the boot @ the CSI unit had a large crack fixed that car runs 99% better.
it revs slow from a roll it just pulls slow and has a hard time getting to the red line what do I need to check next the person that I got it from thought the cat was bad that was not the case,it was the cis boot could you make some sugestions Thanks

Sat Jun 21, 2008 12:49 am

I saw this post other day but since no one else answered yet I'll try now:

There is a set of micro switches on the throttle body, one for idle and one for full throttle, if those mess up they can cause running problems.

I think I'd start with the basics, making sure the air cleaner is clear, the spark plugs look good (I like Bosch F6DTCs on those) the plug wires are in good shape and check out electrically, that there isn't any oil seepage into the distributor (common problem on 16V) and verify the timing is right. Then you can dig in further, like checking the O2 and knock sensors, the potetiometer in the airflow meter, doing a fuel spray and delivery test on the mechanical injectors, fuel pump delivery test on the in-tank transfer pump and main fuel pump pressure test. That's a lot of things, admittedly. Having a factory repair manual to check all that stuff out is a must.

-Andy

Sat Jun 21, 2008 5:05 pm

Thanks I do have some oil in my cap and in the dis.
how do I correct this Thanks

Sat Jun 21, 2008 5:13 pm

Well, I'm not sure if that would cause your missing at high speeds but it's possible. Often when you get oil contamination in the distributor it'll be doing things like not restarting when the engine is hot. Or quit running altogether. Cleaning it out with some good electrical motor cleaner (or BrakeKleen, as long as it's the stuff with that ozone-unfriendly tetrachlroethylene in it) will often fix it for a time but it'll come back once it gets contaimnated again. The true fix is to replace the distributor with a new or rebuilt unit. (Used ones, well you know they are going to fail the same way, question is, is it OK now and how long will it stay OK?)

Sat Jun 21, 2008 5:19 pm

The oil in the distributor cap is common on 16v motors. I had one last month burned the end of the rotor button off. I had replaced both O-Rings in the distributor, but they keep leaking. If distriutor is worn out like mine, replace it with a remanufactered. The lack of power problem sounds like its starving for air, if it doesnt sputter or miss, doesnt have spark knock, then it can only be fuel or air, check plugs for fuel....

Sat Jun 21, 2008 8:26 pm

COOL Thanks I checked the plugs and they very light look like new....I think it might be a little lean
i have looked every where and can't see where to adj the cis you both have been very helpful ....cleaned out the dis and it runs 100% better.I just want to adj the cis and get a new dis ....also what's up with the mpg display the best I could get it to read is 12.0 is that right? thanks bro...

Sat Jun 21, 2008 9:43 pm

my 89 gli had the relay fullthrottle fuel enrichment set up like techtonics sells... one time i was doing something in the engine bay and pulled the ground wire off the relay (accidentally)... the car responded the same way. just felt like it was dragging dead weight. popped the hood found it and bam... the car woke right up.

so it could be a fueling issue... did you check the micro switches?

Sun Jun 22, 2008 12:16 pm

I mentioned those micro switches before too, always a good thing to check because they do fail.

The MPG calcluation on the MFI display on the dash, well, that's not actual MPG, it does not have a little flowmeter in the fuel line showing how much gas has been fed into the engine. Rather, it monitors engine RPM and the manifold pressure and then combines that data to calculate an approximate MPG. They are well known for not being accurate. I'd check it the old fashioned way, start a logbook and keep track of how much fuel you buy at what miles and do the math. (It's not hard, I've logged every tank of gas I've ever bought for my cars!)

The CIS adjustment, it's basically adjusting the angle that the airflow meter flap bears against the fuel distributor's piston. It's like a long 3.5mm Allen wrench, but the access hole is blocked by a factory metal cap (usually been removed but may have been re-replaced, which is a good idea to because it keeps dirt out of there) But you don't want to just jump in there and start messing with it. On the first generation of CIS yeah, you could. But on yours you have electronics that also alter fuel pressure inside the fuel distributor. It's something you should do only after you've made sure at least your O2 sensor is working, and requires you have a low-amp-reading ammeter and a piece of wiring loom with a component plug so that you can wire it inline with your differential pressure regulator. That's all in the Bentley manual. If you got it to run OK right now by doing just the intake boot and cleaning the distributor out, I think I'd call it good for now.

I'd definatly buy a Bentley manual for your car if you plan to do much work on it!

-Andy

Mon Jun 23, 2008 10:52 am

Thanks just 1 other question
the car has a hard time running when cold like first thing in the morning air temp is around 75

Mon Jun 23, 2008 11:02 am

Well, cold running - again there's a few things to check in the manual - temperature sensor and that the computer is altering the current to the differential pressure regulator in response to the temp sensor. However it's not that cold outside so it's not going to be that much of a correction. So, then there's the CIS fuel distributor, these tend to get "gunky" with age and often won't flow very well when the engine is first started. THe more times you rev it up high, the better and more even the flow to the injectors will get. This can be seen by doing the fuel pattern spray test on a totally cold engine.