MISSING AT LOW SPEADS - Maintenance and Repair Forum

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MISSING AT LOW SPEADS
Monday, March 12, 2007 10:32 AM
Ok guys I have a mystery for you to solve. I have been having this problem where my car will bog and shudder at low speeds and at idle it will miss. So I started the diagnosis and have come to a stop in the road. Here is what I did. First I replaced the IAC sensor and it did nothing. So then I was told that it was on exhaust leak, so I looked around and came to 2 leaks. I fixed both of them and reset the computer. Still did not fix it. So then I was told to disconnect the first 02 sensor on the header and it FIXED the problem, but was just a temporary repair. So I was told since that fixed the problem that it lies in the engine sensors. So I ran the scanner on the car and get cam and crank sensor codes. I replaced both and pluged the 02 back in and it worked great for a 100 miles or less. So now it is back to its old ways. I checked the plugs and they seem ok. So I have no idea on where to go from here, any ideas?

http://www.overkillengineeringmotorsports.com/

Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 10:56 AM
the car is a 97 sunfire 5 speed with a 2.4

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 11:05 AM
try replacing that first O2 sensor?!?


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Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 11:46 AM
Yep already did that. Should have mentioned it in the first post. But replaced them at around 5-7k miles ago with bosch. I am going to run a vacuum test on it and see what I come up with, but I dont know what else to do.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 1:49 PM
Ok so I read the HANYES manual and I cam up with this. It can be the air filter, fuel filter, ignition, pcv, vacuum. So I ran a vacuum gauge and it read 20, so thats perfect. I took the air filter off and ran it and it still had the problem. So I have ignition, pcv, or fuel. I did replace my fuel filter about 11k miles ago, but my questions are, where is the port for the fuel to check the fuel pressure, Does the 2.4 even have a pcv, also the ICM how do I check this to see if one cylinder is missing. But It definitely misses bad when the 02 sensor is pluged in and when its not it does not miss so that why I am leaning towards fuel. Either a injector, fuel pump,ect.. Any help would be much appreciated at this point.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 2:11 PM
yeah I'm thinking this is a fuel issue, also do a compression check, just a thought.


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Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 2:28 PM
I know this car is has good compression, I think I checked it when I first got it. But I can do it, its not a problem. How can I test the injectors or where is the port on the fuel system for a PSI check.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 4:42 PM
I believe tehre is a port on the fuel rail....looks like a Tire Valve Stem, just bigger


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Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 5:00 PM
There is no way. I looked every where for it. Can some one post a pic. Also this will only tell me if I am getting the correct PSI right? Now if that checks out to be the case then more than likly its a injector correct?

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Monday, March 12, 2007 8:44 PM
correct...this will tell u if it is an injector


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Re: MISSING AT LOW SPEADS
Tuesday, March 13, 2007 5:09 AM
Are you only missing at low speeds? and how low is low speeds?

Re: MISSING AT LOW SPEADS
Tuesday, March 13, 2007 7:16 AM
At idle, with the first sensor pluged in it will miss, I can hear it in the exhaust and the rpm will shoot up from 1000-1500, but it wont stay at 1500 it will just shoot up and come back down but will do it every 4 sec. With the sensor disconnected it runs perfect, so thats why I rulled out the case of a bad motor ( as far as a blown engine). Now when I take off with the sensor disconnected it will work perfect, but with it pluged in I will try driving it normally and unless I give it 3/4 throttle and ease out of the clutch SO slow it will get moving other wise the engine will cut out and the engine it back fire bad, when I mean cut out like it will just about stall and the car will stall. Now if I press the clutch in it will bring the engine back from just about stalling.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Wednesday, March 14, 2007 11:53 AM
you do not have a pcv,it's a cv,i have a 98 cav,had similiar probs. change plugs,and o2 sensors,and you don't have a Schrader valve on the fuel rail.Get a Chilton's manual,shows how to check fuel pressure



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: MISSING AT LOW SPEADS
Wednesday, March 14, 2007 2:54 PM
Whats a CV. also I looked at the haynes manual and I could not find anything. What wound up being the problem on your car.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Wednesday, March 14, 2007 5:11 PM
OK I scanned the car today and came up with 107, 134 and 342. I know 134 is because the 02 is disconnected and 342 is a cam snesor. But 107 is saying a map sensor. Could this be a problem and where would it be located on a 97 2.4. Got a pic?

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Wednesday, March 14, 2007 5:24 PM
cv stands for crankcase ventiliation.,I don't have pics of the MAP sensor but if it's faulty it'll def. cause problems,if the Haynes doesn't show it buy a Chiltons manual



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: MISSING AT LOW SPEADS
Wednesday, March 14, 2007 5:37 PM
I did look at the chiltons and found the location. I believe that it is the porblem, but who knows.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Thursday, March 15, 2007 7:25 AM
Ok i bought a new cam and map sensor and installed them and all is working well. I did get a code 1133. Dont know what that is. If it starts to act up again I am bring it to gm. Thanks for all the help and I will let you know the outcome

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Thursday, March 15, 2007 8:06 AM
Yep still runs like ass. Going to GM tomorrow.

http://www.overkillengineeringmotorsports.com/
Re: MISSING AT LOW SPEADS
Thursday, March 15, 2007 5:59 PM
Bosch O2's failing in 5-7k miles is not unheard of. As a matter of fact I would go as far as to say its not uncommon....might be a place to start?



"The Blue Bullet"
Re: MISSING AT LOW SPEADS
Thursday, March 15, 2007 7:34 PM
Do you think that is the case as when I un plug it the car runs fine.

http://www.overkillengineeringmotorsports.com/

Re: MISSING AT LOW SPEADS
Thursday, March 15, 2007 7:34 PM
oh I forgot I replaced it when I had this proble, so It cant be it.

http://www.overkillengineeringmotorsports.com/
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