1994 Chevy Full size Blazer

[PaulQ]

Need some serious help on this one. Just replaced my heads and intake on my 94 Blazer with vortec heads and intake. The problem seems to be either timing or valves not sure which. Set my timing multiple times and the truck fires right up and idles fine in park and drive but have no power to go when in gear. Is there a connector that needs to be disconnected while setting the timing or are my valves that tempormental. I adjusted my valves multiple times, by the chevy service manuals way and with the motor running. Neither seemed to fix the problem. Also receiving a backfire in the carb when gunning the motor at around 3500rpm. Any advice would be great.

 

Paul Q.

[dougmac]

Paul

You will need to disconnect the timing connector when you set the timing. The wire is a tan wire with a black tracer. I believe you will find the connector located inside the cab, on the passenger side, under the dash, near the heater box.

 

Doug

[PaulQ]

Doug,

 

I appreciate your advice on this. I already did and I believe I actually traced it to the computer behind the dash on the passenger side in a connector with a bunch of other wires, however it was late and dark when I did and I'll definitely look into in the morning. Assuming your right, when I disconnect then what?

 

Thanks man,

 

Paul Q.

[dougmac]

Paul,

It should be a single wire connector. If you are looking at a connector that has more than one wire, it not the one. I have also seen them under a plastic panel on the firewall, passenger side around the heater.

 

Disconnect it and check the timing with a timing light.

 

Doug

[PaulQ]

Paul,

It should be a single wire connector. If you are looking at a connector that has more than one wire, it not the one. I have also seen them under a plastic panel on the firewall, passenger side around the heater.

 

Disconnect it and check the timing with a timing light.

 

Doug

 

<{POST_SNAPBACK}>

 

 

[PaulQ]

Not it Doug, not on the passenger firewall and I traced it this morning to the ECM behind the glove box in the connector I was telling you about. The fan shroud also says to remove the two pin connector on the back of the distributor however it either kills the motor when running or won't allow it to start. Still at a loss, this sucks.

 

Thanks,

Paul Q.

[dougmac]

Paul,

Email your email address to me by clicking on my name and going to the "Send Email" link.

 

I will look tomorrow at work to see if I cans help solve the mystery. I can then send you an email with what I find from work.

 

Doug

[PaulQ]

Doug,

 

Thanks for all your help, the connector was actually in the passenger side cab taped to the bundle. I guess I missed it the first few times.

 

I ended up taking it in because it just didn't run like I thought it should and come to find out my valves either need MORE adjusting or I got a bad lobe on my cam. I'm starting to think that its a bad lobe unless you know of someway to verify it without spending a ton of money.

 

Thanks Man,

 

Paul Q.

[dougmac]

I don’t know how much help I can be but here are a couple of ideas that come to mind……

 

Have you thought about it being a lean condition? Maybe low fuel pressure or a vacuum leak. If you had a scan tool that could check the fuel trim, it would let you know if it was running lean.

 

Does it have any codes?

 

An engine vacuum test is a good test that I like to use to pick up mechanical problems. You might want to throw a vacuum gauge on and see what you come up with.

 

You said you installed vortec heads and intake. How does the way it runs now compare with the way it ran before? Did the change affect it in a negative way?

 

The only way I know to check for a worn cam lobe is to remove the valve covers and rocker arms then check the lift.

 

I hope this helps,

Doug

[PaulQ]

Doug,

 

The GM Tech did a number of tests and showed I guess what was a vacuum leak or loss on the 2,4,6,8, side of the head and he seemed to think it was either valve adjustments or cam lobe.

 

I tweaked on the valves a little more last night and got it to run a little smoother, but still has a rough idle and definitely doesn't want to give me more power at higher speeds(40-50+MPH), also not really that good at the lower MPH either but better than the higher end.

 

It's to hard to tell right now as to how the truck is running vice before the change due to whatever problem this is. However it definitely feels like there is more power there I just can't get at it yet.

 

Also no service engine lights or any other codes I know of showing up at the moment.

 

I think I'm just going to replace the cam and see what happens, I mean a new cam thats better than stock can't be but so bad. What's your take on roller rockers( yeah or neah)?

 

Let me know,

 

Paul Q.

[dougmac]

Paul

You may be able to cure it without a cam, provided it's not worn out. If you are going to replace it, now is as good of time as any.

 

Actually I’m probably not the best guy to ask about roller rockers or performance cams. I don’t have much experience with engines that are built up. I have more experience and resources for keeping the stock trucks running. There is probably some one around here that can help you out with that better than I can

 

Good luck,

Doug