I've search and read many of the posts here but am still unable to fix my car.
It's a 95 Sunfire 2.2L Auto. The engine staggers, or vibrates, or shakes, whatever is the correct term, when I'm trying to maintain speed. If I step on the gas more, the staggering/vibration/shaking disappears. The samething also happens when I go from idle by applying light gas. If I apply more gas, the problem is gone. In brief,
the engine hesitates when applying light throttle.
I have replaced fuel filter, O2 sensor, MAP sensor, IAT sensor, spark plugs and wires. I tested the IAC with ohm meter and it returned with good reading (~~50ohm). I cleaned the K&N air filter and sprayed cleaner inside and out of the intake manifold. I checked the vacuum lines and did not see any cracks. I tested the ECT sensor which also returned good reading. I have also poured STP fuel system cleaner into a full tank of gas and have ran more than 65 miles since.
I replaced the spark plug wires one by one so I don't think I have messed them up.
There is no CEL.
What should I do next, other than bringing it to a shop?
Any information, any help appreciated.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
Went ahead and replaced the TSP sensor today and hesitation is gone at crusing speed. It still hesitates a bit when accelerating at light throttle and idling is still rough. The only thing I can think of now is the EGR valve. I can push the diaphragm in and out with moderate effort but can't really tell if it's good or bad.
Again, any information appreciated.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
I was going to say TPS but you beet me to it. And it still does it a little? hmm?
have you tried disconecting the battery after installing the new parts? Sometimes the computer can "learn" from a defective sensor and try to compansate for it then when you install the new part the computer still " thinks " its dealing with the old one and does't straighten inself out. Try the battery disconect and let me know what happens.
Leave it off about 10 min with the headlight switch turned on that will drain anything left
let me know what happens.
Semper Fi SAINT. May you rest in peace.
jackalope wrote:have you tried disconecting the battery after installing the new parts? .
Thanks for the reply. I disconnected the battery and let it sat overnight after I've installed the TPS. The problem is still there. I paid a bit more attention while driving to work this morning and noticed the hesitation is only noticeable below 3000 RPM. I can easily reproduce the problem by applying light throttle as long as it's under 3000 RPM. If I step on the pedal the problem is gone.
I am thinking maybe it's the EGR valve, but according to what I've read so far, a faulty EGR valve will almost always throw a CEL, and the car would stall at deceleration in addition to hesitating at light throttle. My car isn't giving a CEL nor stalling.
How can I make sure the EGR valve is faulty? Is there a better way to test it other than pushing the diaphragm? Where else should I look?
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
What other parts than EGR valve could cause hesitation at light throttle?
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
Still no codes? have you tried running some fuel injector cleaner thu it yet?
Not sure about the EGR so I wont guess at it. Anyone else have any ideas?
Semper Fi SAINT. May you rest in peace.
jackalope wrote:Still no codes? have you tried running some fuel injector cleaner thu it yet?
Nope, no codes. No CEL whatsoever. Have also driven more than 200 miles with full tank of gas mixed with STP fuel system cleaner.
Also checked PCV valve last night and it was good.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
I give man. You got me, Without actualy being able to check it out myself I don't know what else to tell you. I'm sorry. But it sounds like you've hit on everything I could have thought the problem may have been. I wish you luck in figuring it out.
Semper Fi SAINT. May you rest in peace.
Check your wires going to your IAT sensor. GM puts the crappiest wires ever they and they break fairly easily. I was having the same problem in my 04. Order Wells part number 235 from autozone 12.99 got the new pigtail put it in and bam no more problems with hesitation. There is a thread on here that goes into this same issue.
I don't need no stinking SIG. Wait this is one.
DOH!
CAVolution wrote:Check your wires going to your IAT sensor.
Well...I've just checked the IAT sensor wires with a volt meter and it returned with good reading (~~4.99V).
I can't think of anything else. Probably just need to go ahead and spend the money on a EGR valve.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
The EGR is weird, wont always throw a hard code. Scan this vehicle as there prolly is a code, but not a hard code, thus no CEL (which stands for the light, not the code)
Then check the wires going to the IAT and the EGR as they are together. wiggle them and see if you can replicate the issue.
Also a free check is to take off the 2 ground wires (one from the block and one from the body) and clean em up and put em back.
Vibrations often casue this issue you are describing.
Vinay Mal wrote:Scan this vehicle as there prolly is a code, but not a hard code
What scan tool should I use on this OBD 1 when there's not CEL?
Vinay Mal wrote:Then check the wires going to the IAT and the EGR as they are together. wiggle them and see if you can replicate the issue.
I have checked the IAT Wires and they returned with a good 5V reading. I have a '95 and it is the only year that has an EGR Control Solenoid where the wires go to. I tested the wires and it returned a reading around 11V. I have Chilton and Haynes manuals but they don't indicate what voltage should that be. Does anyone know what the correct voltage should be for the wires to the solenoid?
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
alont wrote:This is a link which describes how a fault on my '93 2.2 was fixed with a new crankshaft position sensor-just in case it is your problem
Oh my goodness, this POS car has more sensors than my pimples!
Thanks for the information. I'm going to check it out.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
Well....EGR valve replaced and problem is still there. Gonna try EGR Solenoid next.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
Ok...EGR Solenoid replaced and still no fix. I'm moving on to ignition coil next.
My question is, this is a 1995 2.2L, and the ignition coil pack is located in the back of the engine and just above the oil filter. How do I remove it? By looking at it I think I might need to remove the entire intake manifold. Has anyone done this before and how did you do it?
Thanks...really wish I could get this fixed and move on.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
dont have to remove the intake manifold. Just reach down around andpull the plug wires off then take off the screws
Post what the solution when you find it .. Im dying to know ...
Vinay Mal wrote:Just reach down around andpull the plug wires off then take off the screws
I didn't know you could unscrew it that way. It was a PITA just to reach down and remove the wires. I'm gonna try it tomorrow morning.
Quote:
Post what the solution when you find it .. Im dying to know ...
@!#$...me too.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
I did a bit more searching on this site and found that I could bypass the intake manifold by tilting the engine forward. Basically I had to unbolt the upper and lower engine mounts, and jack the engine up from behind. It was still hard to reach the coils but at least my arm could go in there without losing a piece of skin.
Now, here's the coil packs removed:
As you can see, #4 is shot. #2 looks better but it's corroded as well. When I tested #1 & #4 with a DVOM, no reading was returned unless I could pick a clear spot from #4. #2 & #3 still returned a reading of approx. 6,000 ohms but #2 is correded as well so I replaced them both.
So you think that would solve my problem once and for all? We (me and 2 other neightbours) thought so, too.
Nope. After we put everything back together, I started the engine, put it to drive, the hesitation returned. Same deal:
hesitation at light throttle.
We are going to jack up the engine again tomorrow and replace the ignition control module. Stay tuned.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
CAVolution wrote:Check your wires going to your IAT sensor. GM puts the crappiest wires ever they and they break fairly easily. I was having the same problem in my 04. Order Wells part number 235 from autozone 12.99 got the new pigtail put it in and bam no more problems with hesitation. There is a thread on here that goes into this same issue.
Just wondering where you got the IAT pigtail from? Also, did you have to hard wire it or does the pigtail just plug into the main harness?
PROBLEM SOLVED!!
Here's the bad guy, the Ignition Control Module:
I don't know a way to test it but after putting in a new one, the car doesn't chokes on idle and no hesitation on light throttle anymore.
With all the other sensors that I've replaced I guess this car will last me for a while.
I sincerely appreciate everyone who responded to this thread and many thanks to the nice people who contributed to all the information on this wonderful website!
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
Way to go!
Thanks for posting the answer, it's bound to help someone else.
Alont
well its good that you got it fixed but for future refrence the easiest way to get to the ign module w/o pulling motor mounts is to pull the power steering pump off then you have plenty of room to reach into the back of the engine bay from the side.......
sorry i didn't post this before...................
2Blue Cavy wrote: the easiest way to get to the ign module w/o pulling motor mounts is to pull the power steering pump off then you have plenty of room to reach into the back of the engine bay from the side
Thanks for the information. I will keep that in mind. I'm sure it will help many others in the future as well.
<a href="http://www.cardomain.com/id/cting76">My Sunfire</a>
