# Car shakes when cold



## alexnds (Oct 1, 2005)

Gents,

Need advice. Didn't replace fuel injectors yet, and will do so very shortly. My car seems to shake, pretty violently somewhat, when cold. Then, as she warms up, it gets better and better and it goes away almost completely but not entirely.

I thought it was almost like a misfire, but I recently replaced all the spark plugs, wires, distributor cap and rotor, and PCV valve, gas filter, and air filter: in other words, complete tuneup. No wires on any spark plug are loose, and I've checked that repeatedly. 

(Previously dealer said one injector was showing 17 ohms and the others 12 ohms). Techtron fuel cleaner in the fuel tank and on the car fuel injection flush directly into the fuel rail didn't seem to do alot of good, but it smoothed out marginally, but not completely. 

Why does it seem to happen only, and is worse, when the car is cold though? In other words, I suspect a fouled injector on one cylinder as the culprit, but it could it have something to do with EGR? Any advice appreciated.


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## internetautomart (Mar 8, 2004)

I'm thinking coolant temperature sensor.


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## OnTheRoad (Dec 19, 2005)

Also check oxygen sensor. They have a tendency to go out after 10 years.


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## bigern45 (Oct 25, 2005)

have you tried disconnecting injectors one at a time to see what effect it has on your shake? if you are at all mechanically inclined, this is not very hard to do, you might even try to do it while the car is running. unhook the injectors one at a time and see if there is one that does little or nothing to effect the engine performance. if you remove spark or injector pulse from any given cylinder in a perfect running engine, a noticable shake or misfire should be apparent. if you remove one from a cylinder on your engine and nothing happens, you have found the cylinder causing the shake. then check that cylinder for spark, fuel injector pulse and fuel injector operation, and last, cylinder compression. if they all start running bad to a degree when spark or fuel is removed from a cylinder, you could have an egr valve stuck partially open. you could also have a blown headgasket. sometimes when the vehicle warms up, the gasket material will seal to a degree and a misfire not be as apparent once the car is warm, but runs really poor when it is cold


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## alexnds (Oct 1, 2005)

*Fuel injector problem*



bigern45 said:


> have you tried disconnecting injectors one at a time to see what effect it has on your shake? if you are at all mechanically inclined, this is not very hard to do, you might even try to do it while the car is running. unhook the injectors one at a time and see if there is one that does little or nothing to effect the engine performance. if you remove spark or injector pulse from any given cylinder in a perfect running engine, a noticable shake or misfire should be apparent. if you remove one from a cylinder on your engine and nothing happens, you have found the cylinder causing the shake. then check that cylinder for spark, fuel injector pulse and fuel injector operation, and last, cylinder compression. if they all start running bad to a degree when spark or fuel is removed from a cylinder, you could have an egr valve stuck partially open. you could also have a blown headgasket. sometimes when the vehicle warms up, the gasket material will seal to a degree and a misfire not be as apparent once the car is warm, but runs really poor when it is cold



Thank you indeed very much for your suggestion. I think you're on the right track. You see, I did the spark plug test already on my own, but I didn't do the fuel injector test like you suggested. I wanted to see if one cylinder misfiring was fuel injector related, or spark plug related. So far, pulling spark on all cylinders resulted in same basic condition, except the #5 cylinder, as label from distributor cap shows it to be #5. By pulling out that one, motor just stops, and quits, but doing one at a time on the other ones, it doesn't do that. Also, you're right about warming up. As soon as she is much,much warmer, she settles down considerably and it's almost, but not quite, like the problem is not there, but when she's cold, the problem is much, much worse. Even the exhaust pulses abnormally. I think that the motor is running on 5 out of 6 cylinders most of the time, as fuel is probably basically absent from one cylinder mostly. I leave the engine off and she stays in my garage mostly parked until I can get it fixed, because I don't want to cause a burnt piston from lack of fuel to one cylinder. 

I got an upper and lower gasket kit. I got my cleaned injectors in the mail today. I also got an egr gasket, so as to remove EGR and clean out the gunk with carb cleaner, and then re-install it. Hopefully, I'll know soon where I'm at.

If it's a blown head gasket, what are the symptoms of that? Basically, I'm getting new gaskets and cleaned, but not new, injectors installed this week or next week. Any other things I should look for? Any advice highly appreciated.


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## bigern45 (Oct 25, 2005)

check your anti freeze level- that is one way to tell, although i have seen some head gaskets leak between cylinders showing no sign of anti-freeze leak. you might try checking compression while the engine is cold, which should be pretty easy to do. your egr could be faulty as well, but if it is stuck open at all it would cause it to run not right at any idle speed, warm or cold. it may be more apparent when it is cold, but any unwanted extra air at idle is really noticable, but once you are on the throttle, the problem should go away.


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## alexnds (Oct 1, 2005)

Thank you for all your help. It is very much appreciated. The antifreeze was completely changed out when the water pump was replaced, and the work was done at Nissan dealership. The level doesn't seem. I don't see any green puddles, so I don't think it's leaking. (the problem was present before and after radiator flush and fill, so it was not caused by it I think).

I was told by the dealership's mechanic that one injector is at 17 ohms and all the rest are at 12 ohms, and they seemed pretty certain it was an injector problem. I took it for a second opinion and they too seemed to feel the same. I'm having the second shop replace the injectors, as the dealership is way too expensive, and with fresh gaskets. 

I also requested carb-cleaner be used to clean out EGR valve, and got a fresh EGR gasket, since they have to take the entire manifold apart to get to the fuel rail, and doing the EGR cleaning is not really a big deal I feel. 

What I don't understand is why the problem is so much worse when the car is cold. Also, in nuetral or park, it is not shaking as much as compared to putting the transmission into drive.

My only real hope, to be honest with you, is I spent a ton of money on an old car, and I hope that after all is said and done, I can drive it a little.


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## alexnds (Oct 1, 2005)

*removal of fuel injectors done*



bigern45 said:


> check your anti freeze level- that is one way to tell, although i have seen some head gaskets leak between cylinders showing no sign of anti-freeze leak. you might try checking compression while the engine is cold, which should be pretty easy to do. your egr could be faulty as well, but if it is stuck open at all it would cause it to run not right at any idle speed, warm or cold. it may be more apparent when it is cold, but any unwanted extra air at idle is really noticable, but once you are on the throttle, the problem should go away.


I found this procedure:

http://z31.com/repairs/injector.shtml

for fuel injector removal. However, can simply cleaning the EGR valve help (with carb cleaner) if it's stuck open, or do I need to replace it?


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