Engine stutters

MartinP · Post by **MartinP** » Sat Feb 02, 2008 10:55 pm

Hi Guys!

I've seen a couple of similar threads around here, but none of them described exactly the problem that I'm experiencing so I thought I write my own to be sure of what to do. Also, I don't own a turbo, but a -87 ES so that might change some things too. Ok, here we go:

- When I press/depress the throttle I get one powerful stutter that is especially noticed on the 1st and 2nd gear. It disappears sometimes when I do it more softly, but not always.

- Another stutter, just as noticable, around 1200rpm when revving down.

- Less noticable, but rapidly followed stutters when driving very slowly.

What I've tried:

- Change ECU
- Change spark plugs, distributor cap, cables
- Changed temp probe and checked the cable belonging to it.
- Cleaned throttle body, intake manifold and idle valve.
- Changed pulsair valves.
- Cleaned all earth spots.

And everything is just great. The car runs lovely besides this stutter problem and it's driving me mad!

I'm all out of ideas and could really use your help guys.

Thanks in advance!

MartinP

chris1roll · Post by **chris1roll** » Sat Feb 02, 2008 11:20 pm

Looks as though you've changed almost everything bar the engine wiring loom

Injectors?
Throttle postion sensor adjustment?

MartinP · Post by **MartinP** » Sat Feb 02, 2008 11:32 pm

All I've done to the Injectors is check the resistance on them and clean them.

Wouldn't a throttle position sensor adjustment change the idle rpm? As I said, my idle rpm's are just great (~800) and the resistance measured on the sensor is right too.

What about the flywheel sensor? Could it have anything to do with this becuase I haven't touched it.

piper1st · Post by **piper1st** » Sun Feb 03, 2008 9:06 am

Dan the 480 Man recommended i clean the Crankshaft Sensor as they are often a weak spot for this type of problem, didn't do it for me, but worth checking cos it's an easy 30 minute job (if that)!

MartinP · Post by **MartinP** » Sun Feb 03, 2008 11:13 am

So I gave the crankshaft sensor a good clean as the tip was all black and dirty til it became as good as new and the funniest thing was that the engine sounded different. I couldn't really pinpoint what it was, but I've had this car for some time now and I noticed it right away. What's even more funny is that for a short while, the stutters were gone. I drove inside the garage for a short while with both the 1st and reverse and it felt completely different so I decided to give it a good spin to make sure. When I got out of the garage, it was as if I had never cleaned it. Same same.

chris1roll · Post by **chris1roll** » Sun Feb 03, 2008 1:03 pm

So its related to the engine being under load then, as presumably to "drive" it in the garage you had the wheels jacked up?

hmmmm.

Another thought, have you considered removing the pulsair system altogether? Its rubbish anyway.

MartinP · Post by **MartinP** » Sun Feb 03, 2008 1:44 pm

Another thought, have you considered removing the pulsair system altogether? Its rubbish anyway.

No, I haven't since I didn't think that would change anything. Won't that jeopardize the annual checkups when they make a exhaust measurement? I know it's really stupid, but the pulsair system makes the CO percentage seem lesser than what it really is, right?

Besides, I highly doubt it has anything to do with my problem.

So its related to the engine being under load then, as presumably to "drive" it in the garage you had the wheels jacked up?

No no, when I mean drive, I mean it literally. The garage my car's parked in is multi floor parking lot with booth's in it.

EDIT: I just thought of another thing. Could the CO percentage have anything to do with it? I mean, the percentage directly reflects the mixture and the mixture sure has a big influence on how the engine runs. My CO percentage at the moment is 0,3 which is very low as a value as high as 3,5 is tolerable here in Sweden. What if I cranked it up to.. say 2?

piper1st · Post by **piper1st** » Mon Feb 04, 2008 12:52 pm

MartinP wrote:What's even more funny is that for a short while, the stutters were gone. I drove inside the garage for a short while with both the 1st and reverse and it felt completely different so I decided to give it a good spin to make sure. When I got out of the garage, it was as if I had never cleaned it. Same same.

yup ... same here!

I have all the same symptoms as your 480 ... so it could well be we have the same issue. I'll try help as much as i can, but i'll defoe keep an eye on your thread!

MartinP · Post by **MartinP** » Mon Feb 04, 2008 5:58 pm

I adjusted my CO percentage today from 0.8 to 1.5-1.8 and although it didn't affect my problem at hand, it lowered my fuel consumption ALOT according to the computer. Don't get it, why would an increased CO percentage decrease the fuel consumption?

I'm gonna check the condition of the crankshaft sensor tomorrow to see how dirty it is. If it's sh**ty again, I'll get some help from my pal and clean the flywheel my rotating it manually.

SMOOTH 480 · Post by **SMOOTH 480** » Mon Feb 04, 2008 6:11 pm

do you have an after market air filter ?
im not sure if it affects the volvo engine but my swift had a major stutter and didnt want to rev smoothly when i had an over sized filter on

Just a thought but i guess best bet is the crank sensor

MartinP · Post by **MartinP** » Mon Feb 04, 2008 7:03 pm

No, it's a stock filter.

Just a thought but i guess best bet is the crank sensor

What you mean? Is it possible for a crankshaft sensor to get dirty that fast? I mean, we're talking 2-3 mins of engine running.

SMOOTH 480 · Post by **SMOOTH 480** » Mon Feb 04, 2008 10:05 pm

hmm maybe it wouldn't get that dirty that quick

altho it might be a faulty item ???

also what about the fuel filter and fuel pump

just thinking that if you have cleaned the throttle and all the other parts what about the fuel supply when the engine is under load

MartinP · Post by **MartinP** » Tue Feb 05, 2008 4:44 am

hmm maybe it wouldn't get that dirty that quick Confused altho it might be a faulty item ???

I've measured the resistance on it which doesn't show anything suspicious. Is there any other way to is if its ok or should I just try to replace it right away?

just thinking that if you have cleaned the throttle and all the other parts what about the fuel supply when the engine is under load

Wouldn't a faulty pump or filter be noticable when accelerating? During acceleration, my car couldn't be better than what it already is.

EDIT: Don't know if this changes anything, but I've noticed that the stutters are worse when the engine is cold. Then, the stutters appear as soon as I remove my foot from the throttle.
I've tried bypassing the plug on sensor to make sure that it's not caused by a bad contact by soldering the cables directly to each other, but that didn't do anything so it can't be the crankshaft sensor. What about the injectors? Could they be causing the stutters?

@Smooth 480: Just to make sure, I changed my fuel filter today. Nothing.. Sure, there's a noticable difference when you push the pedal to the metal, but the stutters are the same.

EDIT2: Tried switching the coil and the module controlling it, but it's still the same sh*t. This thing is really starting to piss me off

what the hell could it be? I've thought about the EGR valve since I have it disabled atm as its broken, but one of my pals had his disabled too for a while and he didn't have these problems at all so that can't be it. Anyone? I'm getting desperate here...

MartinP · Post by **MartinP** » Fri Feb 22, 2008 6:21 pm

I an attempt to solve this problem I continued towards the next suspect, or in this meaning, suspectS. I'm talking about the injectors. I talked to a pal of mine which in turn talked to his pal and both said I should swap the injectors to make sure that they are working. So I got four along with the manifold off the scrapyard and swapped them today.
Imagine my suprise when I turned ignition key after the whole thing and the engine didn't want to start

I kept hearing the starter and nothing else.
Since I bought a fuel pump of the scrapyard too, I swaped that one too and now I could hear the sound of one or two cylinders igniting when I turned the ignition key, but the engine still refused to start. After 4-5 seconds of starter'ing I heard a deafening sound coming from the back of the car. WTF was that?!

I immediately realized that was the sound of petrol backfiring and so I said to myself "time to talk with the guys".
So guys, what the hell is the problem here? Could it be that the scrapyard gave me faulty injectors? This would be really weird as these injectors were disassembled and checked by the scrapyard themselves, but what else could it be?
I've double checked all the connectors after the whole disassemblement and everything should be fine.

Throttle position sensor - Check
Air temperature sensor - Check
Engine temperature sensor - Check
HT leads - Check
Injector cables - Check
All hoses connecting to the inlet manifold - Check
Idle Valve connector - Check
Crankshaft sensor - Check

Right, almost forgot. I got it to start up one time and I could clearly hear that it was only working on two cylinders. When I turned it off it refused to go back on.

Another thing. When I was reseating the inlet manifold I accidently two of the tightening nuts (those holding onto left and right end of the manifold) meaning that the manifold is only tightened by 3/5 nuts. Could it be that the inner two cylinders are sealed and therefore ignite whereas the remaining two leak so badly that they won't ignite?

666VIVA · Post by **666VIVA** » Fri Feb 22, 2008 7:34 pm

Injectors tend to sieze if not used for a while where the fuel goes hard, fuel additive usually cleans them.

If you have a problem accelerating have you checked, fuel filter or then fuel pump, someone put an injection one in my turbo which stuttered the engine on boost.

Clive

MartinP · Post by **MartinP** » Sat Feb 23, 2008 1:02 am

I didn't have a problem accelerating at all, the car worked excellent that's the thing. And now, well it's not working at all so there's not much accelerating at hand.
Ok, so how exactly do I clean the injectors? I assume that you're talking about cleaning them not only on the tips but also inside.
What about that manifold thing I described last thing I mentioned? Could that have anything to do with my current problem?

JohnTurbo · Post by **JohnTurbo** » Sat Feb 23, 2008 11:07 am

You could try removing the injection rail then turning the engine over...look at the spray patterns of the injectors, should be a nice cone.

MartinP · Post by **MartinP** » Sat Feb 23, 2008 12:20 pm

Yeah, didn't think of that

Then I'll know which one to clean. I'll clean them all anyway while I'm at it, but atleast then I know for sure which one's faulty. Thanks, I'll post back as soon as I'm done.

MartinP · Post by **MartinP** » Mon Mar 24, 2008 10:09 pm

Ok, it took a while but now I've cleaned and replaced all the injectors. The spray pattern are awesome. Still no change.

fredros · Post by **fredros** » Thu Apr 10, 2008 8:44 pm

Lambda sensor?Vacuum pipe lines conected to air inlet?