I've noticed that since I've done my mods this winter that if my engine is cold (ie. under 140* coolant temp) when I hit the gas the engine will bog way down. If I'm stopped it'll take about three seconds and then kick in. If I'm going and let off of the gas for a turn and then push it back down the engine will stall. I thought I could live with it, but it's almost got me into a few accidents in the past week and I need to get it fixed before my car gets into a situation it can't get out of. Any help would be greatly appreciated. Thanks

codes were checked and I'm getting a 43 Knock Sensor or Electronic Spark Control

OK, here's another clue, something I just noticed. When I turn the key to the on possition without starting the engine the radiator fans come on. I did mess with one of the relays a few days ago to hook up my electric water pump, but there are two relays one for each fan and both fans were on.


OKguys I really need your help. it was idling around 400 kind of choking every couple of seconds and recovering. I let it warm up to 170* but I had to rev it for a while because the cooling fans were on. and then I took it for a little spin to the store. I'm not sure if there was any loss of power since it was raining but it idled VERY rough. And when I accelerated I herd a few thuds from under the hood. I'm not sure how to discribe it, but it almost sounded like something hit the underside of the hood. and when I was driving the car was getting rough. EEEEEEEERRRRRRRRR now I'm frustrated :mad :mad :mad if anyone can give me anyclue as to what it is I would greatly appreciate it.

PLEASE HELP :cry


Another thing I've noticed, sorry I'm updating things as I notice them, if the car's coolant temp is above ~100* it seems to do fine and not get stuck in the cold start mode. Maybe it never goes into it and doesn't get stuck in the mode. compared to some sensor being off telling the computer it's colder than it really is. Oh, and I dumped a bottle of octane booster into the gas tank and it seemed to take care of the thuds and rough idling. So possibly my knock sensors aren't functioning and need to be replace as a seperate issue in itself. I've got an appointment to take it into the dealership tomarrow to fix the cold start thing. I'm keeping my fingers crossed adn hoping it wont cost me more than an arm and a leg.


Well, the verdict has come back from the dealership. It was the camshaft. I'm running to large of a cam for the stock programming. The MAP sensor was reading a high load so it was dumping more fuel in. So I sent something out to Ed Wright. I wanted to wait until I got a few more mods before I got the custom chip, but I guess I don't have too much of a choice. Hopefully by friday I'll have a new chip.


[Modified by mn_vette, 8:08 PM 4/27/2002]


[Modified by mn_vette, 8:18 PM 4/27/2002]


[Modified by mn_vette, 1:41 AM 4/29/2002]


[Modified by mn_vette, 4:00 PM 4/30/2002]

 

Could this have been from the new cam? Maybe the TB bypass? or I screw up something simple like a throttle cable length?

theory says: getting suck in cold start mode


[Modified by mn_vette, 6:07 PM 4/27/2002]

 

One other tid bit that might help, I threw it into neutral as I was comming to a corner hoping that it wouldnt stall and I noticed that the RPM's were at 1200. Please help, it stalled 3 times on the way home from work, very embarrasing.

 

if you can confirm that your throttle is OK, which i assume it is, a quick check you can do is fuel pressure. one possibility is that your fuel pump is on it's way out, or possibly just a lot of crap in your fuel filter.

hope you find the problem! :cheers:

 

Your engine running 1200 rpm's in neutral sounds pretty high. I think normal is 700 to 800. This could just be your engine switching to warm-up mode trying to get the cylinders hot. Does your car ever reach good operating temps (170-180)?

 

it does but after about 5-10 minutes of operation. it'll be around 170+ depending on the driving, highway/city. But the drive to work is 5 minutes so I haven't seen it in a while. What tells the computer that the car is in "warm-up" mode? it might give me a good place to start looking thanks

 

"warm-up" mode monitors coolant temperature and adds a bit more fuel and increases the target idle speed when the engine is cold. my LT-1 also has a higher idle if i have any sort of vehicle speed. so, if you're seeing high idle when you're going around a corner, this might be normal. 1200 still seems a bit high though. when my vehicle moves, idle goes to about 1000.

how about checking your ECM for codes?

 

I just pulled one of the plugs and guess what. It was blacker than night. I guess it is getting to much fuel, now I have to figure out which sensor is telling the ECM that it's cold. Any thoughts?

 

Possibly your short drives are causing it to always run rich which is loading your plugs and more importantly your O2 sensor.Id bet on it.
Now its so clogged that its stuck lean telling the computer it cant smell gas.then the computer tells the injectors to lenghten the fuel shot.
:chevy

 

isn't there a error code that comes on if your o2 sensor is dirty???

 

Your temp is read just from your coolant temp sensor and your oil temp sensor. It doesn't do much good to warm up your car for 5 minutes when you only have to drive to work for 5 minutes, so I see your prob. I'm far from knowledgable on the subject, so I could be off on a few things. Things should get better for you since summer is coming and the temps are gonna climb.

 

code 45 (left O2 too rich) and code 65 (right O2 rich) may be set if the mixture is detected too rich when in closed loop and throttle is above 4%, all for too long (50 seconds) . codes 44 and 64 for lean.

coolant temp sensor codes are 14 (sensor short to ground) and 15 (open circuit).

these codes are for my 92. should be identical to your 93.

just in case, here's a good page about retrieving codes.
http://www.c4vettes.com/ecm.htm


[Modified by tempest, 12:24 PM 4/27/2002]


[Modified by tempest, 12:26 PM 4/27/2002]

 

I checked that this morning and it flashed 12 then 43 then 12 agian. So 43 is the only one I see. And that has nothing to do with the O2 sensors

 

I dont' think the O2 sensors have anything to do with it, but they might get fouled up along the way.

OK, here's another clue, something I just noticed. When I turn the key to the on possition without starting the engine the radiator fans come on. I did mess with one of the relays a few days ago to hook up my electric water pump, but there are two relays one for each fan and both fans were on.


[Modified by mn_vette, 6:06 PM 4/27/2002]

 

TTT new info added in the 1st peice of the post

 

looks like your coolant temp sensor is OK, since you're getting what looks like good gauge readings.

uh, that doesn't sound too good. i hope you are not running under 93 octane with the knock sensor failure.

something else to try - since you mainly do short drives, your evap cannister probably is full of fuel. try taking it on the highway for a nice, one hour drive to purge the sucker.

 

Try hooking the electric water pump to another electrical source.
:chevy

 

good call, I do remember filling up with 91 octane because that's all the station had and I was in the middle of nowhere. I dumped in some octane booster and it took care of the banging, but the cold start stuff is still there. I've got two knock sensors comming, I could have had the dealer test them to see if they were bad, but at $75/hour it is just cheaper for me to replace them myself and see if that takes care of my code 43.