Bad Crank Position sensor?

[nunezfrancisco30]

Would it give out a code or check engine light? I tested the Ohms and it gave out 2.445 ohms. Spec shoes that it should be 540 ohms. The car does react funny when I give it gas, it blogs at first and then accelerates. I had taken it to the shop and they pulled out 3 codes. one for fuel system, another that said bad icv and bad AFM. but I tested those and they seem to work properly. I know im starting to veer off the original question a bit but would that mean its a bad DME then? hope I get help from you guys! thanks!:nice: e30s rule!!!! lol

[Kozworth]

I would think a bad crank sensor would dennote a code. A cel pops up if emissions reach above 1.5 times normal for obd2, obd1 is a bit more lenient.

The cks ohmed 2.445 or 2,445 ohms? Because if it was 2.445 I would say its shorted and shot, and the car probably would not start.

What were the other 3 codes exactly?

If you ran lean, aka intake leaks or low fuel pressure, I could see a bog occuring. I would set up a fuel pressure gauge, rev it at the tb and see how the fuel pressure is when it bogs. Just an idea, but if you disconnect the vacuum line to the fpr, the fpr does not have vacuum assist, and should raise fp about 5-10psi. See if that helps the bogging.

A bad afm might have a "gray market" where the carbon track is worn. The door opens, and where the afm should read x air flow, it gets lost in the worn tracking, and runs lean and bogs. To test the afm, hook up an ohmeter, and move the barn door flap. Resistance should steadily increase/decrease with barn door opening, much like a dash board light dimmer.

[nunezfrancisco30]

Yes it ohmed out at 2.445. But it starts and stays on. That's the weird thing. Where would I hook up the fuel pressure tester?

[Kozworth]

You can just put a T right between the feed line and the rail. Also, I believe the crank sensor needs to be measured with the harmonic balancer. The teeth on the crank would be the source of the triggering signal, which would tell the crank sensor to dme what position the crankshaft is at. I just feel that something so important would have more of an impact then a minor acceleration stumble.

Here is some testing I had just read from the bentley on the crank sensor:

To check the voltage signal, m easure the voltage at the
control unit connector using a digital voltmeter ( 1 0 VAC scale) .
On Bosch control u nits, connect the positive ( + ) probe to
termi nal 5 and the negative ( - ) probe to terminal 6. On Siemens/
Telefunken control u n its, con nect the positive ( + ) probe
to termi nal + and the negative ( - ) probe to terminal - .
With the starter cranking, there should be approximately 1 .0
to 2.0 volts AC. If there is no voltage or the reading is low, check
the continuity i n the wires between the control u n it con nector
and the distributor.

To check impulse generator resistance on Bosch control
units, measure between terminals 5 and 6. On Siemens/Telefunken
control u nits, measure between the terminal + and
terminal - of the small con nector. See Fig. 4-3. lf the resistance
is not 1 1 00 ± 1 0% ohms and no faults are found in the wires
between the control unit connector and the connector at the
d istributor, the impulse generator should be replaced

[nunezfrancisco30]

Wow thanks alot for the help really appreciate it!

[Ryann]

The engine will not start with a bad CPS.

[jlevie]

I don't believe the engine would start or run if the CPS had a resistance of 2.445 ohms. That would mean most of coil in the CPS is shorted out and it's output signal would be almost non existent. Either you are measuring the resistance wrong or your meter isn't working properly. Check the meter against a know resistance.

[IRON-E]

The engine will not start with a bad CPS.

Not necessarily true., I had a bad CPS for a week, car would have enough cranking power to get me moving and get up to 3rd gear, then I would get backfiring and bogging out. Drove me nuts, until I figured it out and replaced the damn thing.

To the OP; have you tried cleaning AFM & ICV? Maybe a bad FPR?

[nunezfrancisco30]

Yes I've cleaned the ICV already, I took the reading with a brand new fluke meter. The way I tested the CPS was thru the dme's input plug( the end of the wiring harness that connects to the dme) is there a way to test it directly?