I hope someones run into this before... Ok I put out my 305 put in a 350, vortech heads, headers, exhaust... blab blab blab but I dont know when exactly it started happening but:

my tach is reading about 1000 rpm more than it is... temp gauge doesnt go above 100... and oil pressure gauge flops between everything it basicly just goes hay wire. It has a weird jumpy idle just basicly revs between 750 and 1250 constintly and my fan just randomly cuts on and off...

you think its my ecm? mabey my thermastat is bad to?

 

Ok the tach thing sounds pretty normal not sure how to fix it but my gfs camaro had that problem too and it wasn't the computer. Has to do with how crappy the stock tach is. The Idle sounds like the oxygen sensor, although if the computer is bad it will do that to. Does it idle funny when cold or only when warm? Not sure on the other stuff.

 

Claw,

The temperature gauge does not rely on the ECM. There is a completely separate sending unit for the gauge that does not connect to the ECM at all (unless you have the digital dash, but then it would be a display, not a gauge).

What fuel system are you using? A failing O² sensor shouldn't affect idle like that, regardless of the type of fuel delivery you are using.

 

I see in your post you change engines check all those nice ground wires the ones on the back of the heads and the ones that are bolted to the themostat housing bad grounds can cause these ghost problems.

 

well I would check and make sure all your senders are connected up right, the temp guage sensor in the drivers side head, the oil pressure sender on the back of the motor, and the coil tap for the tach (although helloriker is right, incorrect readings from the stock tach is common)...as for your idle issues, like vader said what fuel system are you using, if carbed are you CC or on vacuum, if you are on a CC fuel system is your EST wire hooked up (its the brown one with a single pin black weather connector, runs along the top edge of the firewall, just over the heater box on the passenger side)??

 

Well the o2 sensor shouldent do that doesn't mean that it can't Had a problem like that after replacing the fuel pump. When I replaced the o2 sensor it was fixed, granted there are other things that can do that but it did that exact same thing. The o2 sensor on the camaros say they last 60k miles, and it is a fairly quick fix. But then again that was on a 6

 

it says and error 43 which is electronic spark control...?? i have no idea what this means???

 

Well I am guessing at this point your ignition and fuel are still computer controlled? Code 43 means that either the Electronic Spark Timing is disconnected, or you are getting excessive knock, also possible for knock sensor to be disconnected. That could be the cause of your wierd idle problems. When does the SES light come on? Are you running rough under acceleration? Does the motor feel lazy, like the timing is retarded?


Like was asked earlier what fuel/air system are you running? TPI? TBI? Carb, is it CC or Vacuum? Is whatever system you are using still stock? You said you went to a 350 with Vortech heads from a stock 305? Did you update your PROM or are you still running off the 305 chip? The more info you give us the more info we can give you

Also, I have had a bad O2 cause idle surges or idle search issues.

 

its a tbi... how or who can update my prom?

 

ok so you are on a computer controlled set up. you may need bigger injectors for the tbi, plus a reconfigured PROM....I don't think there is a stock PROM for a 350 TBI, maybe a truck had one?..I suggest cruising over to the motor swap board and the TBI board and asking a few questions to those guys. You can check with companies like hypertech, jet, fastchips and a few others that make performance chips.

As to the code your getting and your guages being goofy, see the info I previously posted. Oh one more thing, did you reuse the knock sensor for your 305 or did you get a sensor for the 350..its one of the few sensors that actually need to be changed between the two.

 

Did you have any of these problems before you change the engines if not check your grounds