TheSamba.com :: View topic

Fri Feb 15, 2008 11:07 am

I've got an 89 cabriolet that is hard to start when it's warm and idles rough once it's warmed up. Runs like a top past idle speed. The motor only has 43,000 miles on it and the timing, plugs, cap, rotor and plug wires are good.

Possibly a faulty injector? Any way to test them before I go out and buy 4 replacements?

Might my problem be something else?

Fri Feb 15, 2008 11:32 am

That's the last year for CIS fuel injection. CIS often have COLD running problems, like rough idling on initial startup - due to accumulated varnish and gunk in the fuel distributor - it has to rev up a few times to get flow to all the injectors. However your's is a hot running issue. It could be a bad injector. I'd do a comparison spray test when the engine is hot and you are having the issue. You need to bypass the fuel pump relay so it runs with the key off and pressurizes the system. Then you need to pull the injectors out of the head (the special tool to help lever them out really helps sometimes) and you can also replace the rubber O-rings on the injectors at this time too - even with those low miles, I bet after all those years they are pretty hard and dried up and could even be the problem. Then with the injectors out, aim them at a towel or something to catch the fuel, and with the fuel pump running - you remove the rubber boot from over the fuel distributor and use a pliers to pull the flap up on the airflowmeter. This will send fuel through the fuel distributor to the injectors. They should all start spraying at the same time and have similar cone shaped spray patterns. If one or more of them doesn't spray right away or has that "gunked up Motel 6 Showerhead" look to it, it probably could use replacing.

Also, with the airflow meter released (off), none of the injectors should drip any.

You might have issues with the warm up regulator (air valve) or the idle boost air valves too, that could give some idling problems.

I'd start with looking at those. The Bentley manual really helps to have. Fuel pressure tests on the fuel system require special guages (you need the right fittings, a cutoff valve and a 100PSI gauge)

Andy

Fri Feb 15, 2008 11:39 am

Thanks, Andy, I'll start there and see what I find.