Still no spark=Pearl is parts!

quahog pearl · Post by **quahog pearl** » 15 Apr 2013, 10:22

Well, I am out of ideas on what is preventing a proper spark. Swapped a CPS and coil with known good, ohmed out wiring to and from ECU, swapped in another ECU, new battery, ignition switch, cap, rotor, plugs, wires(bosch and Bougicord). There is a very sporadic, weak spark from the coil, mostly once just as I release key from cranking Starting had been getting progressively worse until I cannot start it at all. I expect I will be selling this car for parts which is truly unfortunate. Once started, it ALWAYS ran great. The 5sp stick makes it so much fun to drive that when I saw a nice S60 with a stick, I bought it.

I have a hard time giving up on anything, but right now I don't know what else to check. Is there some sort of overload/inhibiting switch which would prevent spark during cranking. Pearl is no longer my daily driver, but I want to fix this so I can sell as the strong running car it used to be. Thanks!

Post by **mercuric** » 15 Apr 2013, 13:42

crank position sensor (aka rpm sensor) ?
You mentioned CPS... Did you mean crank or cam sensor?

Post by **BEJinFbk** » 15 Apr 2013, 18:56

Weak spark...Low voltage?

What are you seeing for voltage at the coil?
There should be pretty much the same reading
on the positive side of the coil as what you are
reading at the battery when the key is in run pos.

boksalg · Post by **boksalg** » 16 Apr 2013, 01:25

Unless I'm mistaken the ECU acts as a failsafe measure (as the cam position sensor), but I also believe its heavily tailored to your exact model and type. I'd suggest trying the old ECU as I read you did a lot of swaps.
There are a few parts involved between the ignition key and the spark plugs, and I do not believe the ECU is a part often in need of replacement. You can reset the ECU by removing the battery plugs and touching the cables. Did you reset it after swapping the ECU? After connecting the battery again you'll need the radio code if you're still having the original Volvo radio.

Does the car throw any codes?
Why did you swap the ECU?

Post by **jimmy57** » 16 Apr 2013, 07:55

Have you tried to push start the car?

Was there any repair that separated trans from engine done recently?

Any repairs that disturbed the CMP sensor and CKP sensor wiring?

quahog pearl · Post by **quahog pearl** » 16 Apr 2013, 10:48

Thanks all for the responses. I believe I checked the RPM (crankshaft) position sensor for continuity (does 280 ohms ring a bell?) but I'm not totally sure. I will check again. Codes I had were 214 and 314, both for the CPS. I reset them and they have not reappeared, but that may be because they won't set unless it is running. I have not yet done an ECU reset by disconnecting and touching the battery cables, I will try that also. I have never had a code for the RPM sensor, but I will swap that out also with a known good one as well as trying a third known good CPS - the other 2 sensors have run many miles in this car, so it's not likely but also not impossible that they are both now somehow bad. The spare ECU I recently obtained was from a 95 GLT wagon with 5 sp manual and all the numbers match exactly except the last barcoded one and then only the last 2 digits. Voltage at the coil reads the same in position II and drops about 1V while cranking - normal according to what I've heard. Supplying a jumper between coil(red) and battery+ makes no difference either.

I have not tried push starting the car but that's a good idea. However, pearl is at the bottom of a gravel driveway right now, so I may have my wife pull us with the truck(she's a keeper and a really good sport, but this is gonna cost me a XC70 in blue with tan leather!) I may try jumpering the starter solenoid with key in position II as once it fires, it'll run all day.

The Haynes manual my buddy gave me(along with the swap parts) shows an overload relay in the starting circuit for both tranny types. I don't necessarily trust that manual but perhaps this could have an effect. Does anyone know if there is indeed an overload relay in the circuit and whereabouts might it be?

Thanks again for the suggestions. I'm getting ready to dive in again, maybe this time I can close the loop!

Post by **jimmy57** » 16 Apr 2013, 12:57

I posed those questions due to experiences just like yours.
The crank sensor is not that far away from the starter. THe starter makes a huge magnetic field and is JUST BARELY suppressed by the bell housing and block and the two must have clean contact. The magnetic field not being suppressed cancels a readable signal so the CKP-CMP synchronization never occurs and thus no spark. The noted symptoms of this is the spark when you let go of key and motor goes a few degrees after starter and starter mag field stops. The CKP and CMP wiring can also cause this effect if they are too close to starter battery cable or coil to cap wire.
Faulty starter can cause it as the starter motor dragging causes excess current flow and greater mag field.
Push starting a manual can rule out the suppression or starter faults. It would be unlikely for the bell housing to motor issue to happen if trans was not separated from the motor.

Post by **abscate** » 16 Apr 2013, 14:38

I'm sure you have to run the engine for OBD to detect a misbehaving CPS...it probably has a 'tolerance' for a certain number of 'allowed mistakes' programmed into software before it throws a code and then goes into limp home mode.

Post by **kcodyjr** » 16 Apr 2013, 15:04

Sounds to me like the low voltage side of the coil is fine, there's an open question on whether the CPS is getting a clean signal depending on starter condition, but I see one glaring gap in the analysis, no pun intended.

The high voltage side of the circuit might have excessive resistance. You've replaced the cap, rotor, wires, and plugs, but that's just half the circuit. How about the ground strap on the back of the engine, is it all green and shitty? Battery negative cable?

quahog pearl · Post by **quahog pearl** » 17 Apr 2013, 05:49

Thanks Jimmy, hadn't thought about the magnetic field of the starter. I should definitely swap out the CKS. I haven't yet because the only codes I have gotten are 214 and 314. Also, other posters have mentioned the grounds. Yes, the 2 straps at rear of engine are kind of green and sh***y. The negative battery cable had so much corrosion that it actually separated at the terminal. The sh***y grounds at back of engine were all that was left!

I have since crimped on another end/shrinkwrapped end and that seemed to help for a while. Now, I don't trust it and I will take it back out and crimp and SOLDER it back on. I will also replace one or both of those back straps. I have some trees to murder before the leaves pop, but I hope to get to this soon. Thanks again for all the good ideas. Pearl may not be parts after all