Alternator issue

99_xc70 · Post by **99_xc70** » 17 Dec 2011, 12:50

My car is running rough and missing on 2 cylinders. I tested the charging system and it came back with excessive ripple under load. Does the alternator effect the cam sensor or crank sensor? Mechanical timing is dead on but it's almost like ignition timing is off.

I have codes for random misfire and sometimes misfire on 1 or 2. Compression is good, spark plugs are new, coils and injectors have been swapped and still only running on 3 cylinders. So if the alternator is no putting out enough voltage does that mess up ecu, cam sensor timing? I google search "excessive ripple" and found out alot of Fords have a running rough, misfire due to the alternator being bad and effecting the cam sensor, would this be the same on volvo's?

I am stumped on this problem and cannot drive the car this way. I've spend $300 on a starter, $300 on a rad and now maybe another $300 on a alternator. I know I can get it tested for free but I've had alternators tested before and saying no problem found and there was a problem.

Post by **Ozark Lee** » 17 Dec 2011, 13:06

Normally the battery acts like a big capacitor and filters out the ripple to the rest of the systems. How are all of the battery cables?

...Lee

Post by **jimmy57** » 17 Dec 2011, 13:11

excessive ripple means the diodes are not rectifying the ac current into dc effectively. AC will make for problems.
The charging sytem can be keeping battery almost full charged so that battery seems fine and starts car but still have excess ac current output. Usually the miniscule amount of unrectified ac current creates a measured ac voltage of less than 0.1 V (< 100 mV). The alternator is actually 3 charging windings with two per (some with outputs over 120A can have 4 per) winding. If one of the diodes fails then it effectively takes out 33% of your charge out put but since the voltage regulator will go beyond normal level in this case, some times the loss is only 20-25%.
Anyway, yes if the alternator is faulty it can cause problems.
To see that this is the case, start with decently charged battery with static no load left unloaded voltage level of 12.3 or better.
Remove the skinny wire that plugs onto alternator. Now start engine and see if the problems persist with alternator not charging. Do not go over 2500 rpm or the alternator may begin to charge in spite of having the voltage regulator lead off.
If the problem is still there then take alternator off the list and keep looking for problem.

99_xc70 · Post by **99_xc70** » 17 Dec 2011, 15:10

I already removed the alternator to get it tested. I bench tested each diode and all tested at 0.359 and nothing in the opposite direction. I will reinstall it then and remove the plug from the regulator and see what happens. So if the voltage regulator is bad will it effect the cam sensor? The alternator half works, it says it's charging the battery with no load but with all loads on it's not charging.

I have removed and cleaned every possible ground on and around the engine bay, none were really bad at all. The battery and starter are brand new as well. The battery light is not on either because it is charging just not under and load. With my car running at an idle it has a slight misfire, but as soon as I put in reverse or drive(load) it starts to shake and bang, put it in neutral and it sooms right out but still has a slight misfire. I really hope the alternator is the problem, it's been almost 3 weeks playing with this now to get it to run properly.

Post by **BEJinFbk** » 17 Dec 2011, 16:16

It seems kind of odd that only 2 cylinders are being affected.
Especially on a model known for failure prone coil packs.
You may learn something by swapping packs and rechecking codes.
If the problem follows the packs, there ya go. Issue diagnosed.

99_xc70 · Post by **99_xc70** » 17 Dec 2011, 19:00

I've already swapped coils and it didn't change. When I removed the coils all them have cracks almost down to the spark plug. I know I have to probably change them out but wouldn't the misfire be in all 5 cylinders not just 1 and 2. When swapping coils around it still stays on 1 and 2.

How does the cam and crank sensor work? I know they are suppost to send a signal to tell the ecu what injector and coil to fire when each cylinder is at TDC but I read somewhere one controls 2 cylinders and the other controls the other 3? I can't find the info anymore. So if the voltage signal was incorrect it would mess up ignition timing. The cam sensor reads between 5v and 10v, that's why I think the alternator is the cause of my problem.

By tested the alternator I know there is a problem with charging under load but I just wanted to know if anyone else has had the same type of problem? It seems all info on misfires have never come back with a fix or what caused the problem.

Post by **Pauloil** » 17 Dec 2011, 21:26

Ozark Lee wrote:Normally the battery acts like a big capacitor and filters out the ripple to the rest of the systems. How are all of the battery cables?

...Lee

his last question is the most impt. check your B+ cable and search for the comments on voltage drop

volvo charging problems start with checking the cables. when I did my B+ cable voltage at batt went from 12.3 back up to 12.6 range

http://www.aa1car.com/library/voltage_drop_testing.htm

99_xc70 · Post by **99_xc70** » 17 Dec 2011, 22:19

I did do a voltage drop test and got 0.4v from the B+ on the alternator and 0.2v from the alternator case to the battery negative post. I cleaned the connections first and then did the test. The connections are good it just the alternator is not charging under load. I just want to know if the alternator is not charging properly will that mess with the ecu and cam sensor/crank sensor causing ignition timing problems?

Post by **jimmy57** » 18 Dec 2011, 07:28

IF the voltage gets low it will run bad and miss. Low voltage for this to happen would be 10 volts or less.
The crank sensor registers engine rotation in 6 degree increments, The time between increments is engine speed. There is a place on the sensor ring that makes a change in the sensor out put that gives a reference marker on each rotation. The Crank sensor cannot determine which of the two rotations the engine is in that make up a complete cycle of operating each injector an coil. The cam sensor on that engine has a multi profiled reluctor on cam end and the sensor reduces a signal voltage a few tenths of a volt when the profiles are high (magnetic affect on sensor) and the voltage goes up when the profile is low (no magnetic affect on sensor). The ECM comparison of crank and cam sensors allows ECM to know which cylinder and when to operate the proper injectors and coils. The multi profile cam sensor also can be used as a backup to allow a default running condition if crank sensor fails.

But to get more directly at what you are wanting to know: if the alternator is not charging properly can it make it run bad? Yes, but only when the available voltage to ECM and to the operated components gets low enough.

99_xc70 · Post by **99_xc70** » 18 Dec 2011, 09:17

Ok, so the alternator has a problem but it still will charge the battery all day long with no load so that's probably not causeing my problem. I swapped cam sensors out from my other good running car but not the crank sensor. I measured resistance across the terminals and got around 119.4ohms. I have 2 dead cylinders but have compression, air, spark and fuel. They just will not work together. So whatever controls the ignition timing I feel is my problem. If I had an engine light on other than misfire 2 or random misfire I could at least pinpoint what the problem is. This is getting insane!!! Even if it's the ecu somehow causing this problem I can't even get the thing out and if I do swap the one from the other car is will have to be programmed. I give it another week or it's going to the junkyard. I've always wanted a volvo wagon but this is crazy. I should have looked for an older 850 other something.