when the gm dealer doesnt know?

[irondiezl3]

what do you do when you have a 04 alero that has a rough idle and rougher in drive, feels like its gunna stall between 30-50mph and sometimes has a hard time starting and the gm dealership looks at it three times and doesnt know what the problem is? where do you turn? car has had a full tuneup, 3part fuel system cleanup new 02 sensor, dont know what else to try.

[bigdaddyD]

if it were me, i would check the basics, even though the dealership should have, belt, plugs, wires, air filter, look for leaks. but thats the extent of stuff i know, maybe change the fuel filter, even though it shouldnt be that bad.

[surreal_awakening]

Different dealership? Then contact the regional rep.

[irondiezl3]

sorry forgot to list fuel filter belt was both also changed they said the only vaccuum leak was the intake maifold gasket which they also replaced. both hub assemblys were replaced battery window regulators air filter plugs wires im beginning to believe this was a flood car wouldnt the car fax report have said it was? the car fax was mint on this car which is why i bought it feb 8 and since then its been in the shop foreverything this idle problem is the only issue they cant fix i have no ses codes on so im lost. sorry forgot to state it has 56k and one owner

[bigdaddyD]

see if there was a way to contact the previous owner of the vehicle, maybe you can get some info from them?

[Cliff8928]

No Service Engine Soon light?

[Vinalero]

Loose battery connection? Corrosion on the battery cables?

[irondiezl3]

new battery checks out fine and yea no ses lights wierd. funny thing is the idle gets worse when its in drive. the only thing dealer suggested was maybe just maybe the fule pump isnt putting out the right pressure but said no way to know. to be honest it was very very minimal difference but when i put the new fuel filter in it seemed to get just a tad bit rougher idle but very small difference and i know its intalled correct thought maybe it somehow got air into the line even tho i never heard of that but ive drove it to complete empty couple times to see if it helped and it didnt. idk its got new factory plugs and wires too i stayed factory to be safe. wierd how none can diagnose the issue

[Kanyon]

Mine did that twice. After replacing the throttle body, and when the PCV elbow fell off somehow. Double check the throttle body gasket and the PCV hose.

[billytheman1188]

fuel pump isnt putting out the right pressure but said no way to know.

hmmm......isnt there a way to check the pressure in the fuel lines? I remember last semester we tested the fuel lines in a few of the cars we had in the shop.

[jayson_waltz]

hook er up to a fuel pressure tester. If not that, try a different dealership or contact regional rep.

[Redog]

Yes you can check the fuel pressure in the system, there is a port on the pass side of the motor, but I'm not sure where.

Passlock problems? MAF going bad? My MAF was so bad that when I replaced it the car acted up, chriping gears under normal accel, and stalled out and wouldn't restart. I had to unplug it to restart the car and quickly plug it back in before the car died.

Seems like in your case, vacuum leaks and what not are covered. See if there is a shop around that has a progressive scanner. My new mech has one and they are awesome. :yahoo: Got the problem fixed on a test drive

[surreal_awakening]

4 cyl or 6? If it's a 6, the nipple for the fuel pressure is on the end of the rear fuel rail (closest to the firewall), sticking out from under the upper intake manifold on the passenger side. It has a small black plastic cap on it. Remove the cap and it looks a bit like a larger version of the valve stem on your tires. That's where they hook up a fuel pressure gauge. So if they are saying there's no way to check it they are full of it. If it's a 6, "With the ignition switch "ON" and the fuel pump "RUNNING", the fuel pressure indicated by the fuel pressure gage should be 284-325 kPa (41-47 psi)." Not sure where it's at on a 4, but it will be there somewhere. If it's running that poorly and not throwing any SES lights or codes, it could be a failing ECU. The other option is that it's an intermittent code, and sometimes they don't result in a light, but from the sounds of it, it should be throwing a code.

[irondiezl3]

damn my maf seems clean yea they wont pay to check everything so ill have to check it myself what should i look for ?

[JOEY GLADSTONE]

IAT sensor

[Redog]

^^ Good point also easy to overlook

[irondiezl3]

wouldnt that throw a ses light though?

[SIUlero]

just wondering, does your ses light come on and then go off when you turn on the ignition?

[super white alero1]

Can AZ give you a monitor reading and freeze frame? This would help.

Other items to consider, remove the O2S before the cat and test drive the car. If it runs better you have a locked cat.
Check for vacuum leaks using a 1 can of carb cleaner.
Is you engine making a loud grinding noise from the belt side?
Do you have this problem after 35mph?

[irondiezl3]

i believe it does the light when i first start goes on with all the other lights that go on and off i know it hasnt came on and off though since i got it normally any other time tho. umm the idle is rough always but its rough enough to feel in ur feet once car is put in drive. the only time it feels like its gunna stall out is between 30-50mph thats where the dealer guessed but didnt check that maybe im losing fuel pressure? idk if i had to guess in my opinion the car feels like its just having a hard time breathing but im not mechanic.

[zzyzzx]

I'd be looking for vacuum leaks or a leaky EGR valve.

[JOEY GLADSTONE]

i would cut out your old IAT pigtail and splice in a fresh new one, only like $16 from your GM dealer.

[irondiezl3]

why what affect would a iat sensor have if it was bad? that causes a rough idle?

[super white alero1]

You ECU uses the info from the IAT and you coolant temp. and compares the values. If your coolant is cooler than the IAT value, your SES will trip. It more for fuel economy than anything else. The closer to the filter the IAT the more gas it consumes, Unless you have a true CAI this won't affect you much.
The Intake Air Temperature (IAT) sensor is a thermistor which changes value based on the temperature of air entering the engine. Low temperature produces a high resistance, 100,000 ohm at -40°C (-40°F) , while high temperature causes low resistance, 70 ohm at 130°C (266°F) .


The PCM supplies a 5.0 volt signal to the sensor through a resistor in the PCM and measures the voltage. The voltage will be high when the incoming air is cold, and low when the air is hot. By measuring the voltage, the PCM calculates the incoming air temperature. The IAT sensor signal is used to adjust spark timing according to incoming air density.

The scan tool displays the temperature of the air entering the engine, which should read close to ambient air temperature when the engine is cold, and rise as the underhood temperature increases.

If the engine has not been run for several hours the IAT sensor temperature and engine coolant temperature should read close to each other. A failure in the IAT sensor circuit should set DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage or DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage.

[irondiezl3]

they keep telling me they dont feel it its aparently clear that sumthins wrong. can i go to any gm dealership witha lemon warranty cuz these people arent going to help me or am i stuck