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Re: Bosch or refurb air mass meter? Posted by RS [Email]  (#15)  [Profile/Gallery]
(more from RS) on Wed, 14 Jan 2004 05:23:20
In Reply to: Bosch or refurb air mass meter?, Scott, Tue, 13 Jan 2004 22:29:32 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Before I fully commit myself to any diagnosis, how old are the spark plugs wires, cap, and rotor? How large is the spark plug gap?
I had a similar non-starting condition on my '88 900S, and it was resolved by putting in a fresh set of spark plugs.
If you're in salt country, you could have enough of a conductive coating on the wires to send the spark to ground.
FWIW, if you got the same results with the AMM from the '91, it's probably not the AMM.
One thing that could help is pulling the plugs, pulling the fuel pump fuse, and cranking the engine to dry out the cylinders. When you crank the engine with the fuel pump fuse in, it still injects fuel into the cylinders. If it doesn't start, the gas washes the oil film off the cylinder walls. SO, you'll want to dry it out with the fuel pump fuse out.
In general, check the cheap stuff first.
>1. Is there a way to meter the existing AMM to determine if it is >defective?
Swap in a known good one. The one from the '91 (number stamped into the top ends in 013) will interchange with one from an '88 non turbo. As always, check the numbers on the existig one to be sure.
>2. How useful/diagnostic would it be to rig the jumper/switch to look for >error codes under non-starting conditions?
It may be worth it. It'll be good to have it for future use, if nothing else.
>3. Are there other parts whose demise might cause similar symptoms? Any >way I can test suspect parts to place blame (short of swapping them out >for new parts)?
NTC (Negative Temperature Coefficent) sensor. Located on the intake manifold flange between cylinders 2 and 3. Check the NTC sensor resistance. The values should be in the neighborhood of these:
32F.....5800 Ohms
68F(about 20C)......2600 Ohms
176F......320 Ohms
Vacuum leaks are another good source of non-starting at those temps. Who knows, you may have a shrunken fuel injector O-ring or intake manifold gasket.
>4. I've always believed that 'you get what you pay for' but shudder at >the Bosch price for AMM relative to rebuilt and wonder if the premium is >worth the price?
Well, if you want absolute, optimal perfection, get the new one, but for all practical purposes a rebuilt or a good used one will operate more than satisfactorily. If you're charged more than $80 for a used AMM, then the premium for a rebuilt is probably worth it.
posted by 63.148.1...
, Wed, 14 Jan 2004 05:23:20 <-- Viewing This Message
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