Help. Runs rough and rich at startup. 88 3vze v6 3.0

[10ac]

I have a 88 v6 3.0 3vze. At a first startup while engine cold, it runs a little rough as if its running on less cylinders and i smell a rich gas smell. After its warm from running about 5 min, it runs pretty good. Another thing i notice is my bad gas milage. Full tank i get 200 miles or less. Also i feel like its running rich most time. I smell rich gas smell every now then.
I dont see any gas leaks from cold start injector or injectors on rails.
I have no check engine light.
I have just done new denso spark plugs
Ngk plug wire set
Oem dist cap and rotor.
Planning on doing the timing belt soon with tentioner pulleys and water pump. I can hear a sqeaky sound seems coming from behind timing cover so thats why im doing it. The previous owner said he just did it recently but im afraid of maybe he used cheap china parts that may be failing.
Also noticed it has a new mass air meter. Wonder if that is already failing and causing the running rich issue?
Or needs a oxygen sensor?
Also after its fully warmed up it idles at 1000 to 1100 rpm. Is that correct or is whatever causing it to run rich making it idle high.
I did clean the cold start injector because of the hard starting when its cold. Didnt help. Still hard.
Air filter new as well.

 

[Jt2El46]

Check the cold injector actually block the fuel line leading to it.. It's common that they leak. Check the VSV on the back of the the block, on water cross over. If the PVC tubing is broken it will run rich. Make sure all of your tubing holds vacuum, and that the vacuum line to the fuel pressure reg up behind the right side of the manifold against the fire wall is not off or open.

 

[mholme]

Could be lots of things causing lumpy warm up, IACV comes to mind. You should be around 850 RPM at warm idle. Have you checked timing? You may also want to check for codes, even with no light on.

Also, how are you calculating mileage? Are you getting to about 200 miles and your gas light comes on?

 

[10ac]

Check the cold injector actually block the fuel line leading to it.. It's common that they leak. Check the VSV on the back of the the block, on water cross over. If the PVC tubing is broken it will run rich. Make sure all of your tubing holds vacuum, and that the vacuum line to the fuel pressure reg up behind the right side of the manifold against the fire wall is not off or open.

ahhh i see. the cold injector you say may be just leaking constant in the manifold. i was meaning not leaking from the line connection. i will check those things u mentioned.

Could be lots of things causing lumpy warm up, IACV comes to mind. You should be around 850 RPM at warm idle. Have you checked timing? You may also want to check for codes, even with no light on.

Also, how are you calculating mileage? Are you getting to about 200 miles and your gas light comes on?

right when light comes on, its at about 165 or 175. haven't checked timing tho. ill do that as well. what is the ideal timing degree? i read somewhere that it was best set at a certain degree other than the amount recommended on the hem label??

thanks y'all, i do appreciate the effort helping me out.

 

[10ac]

by the way, what is the size vacuum tubing i will need? i think I'm going to order all new vac line and replace all.

 

[mholme]

right when light comes on, its at about 165 or 175. haven't checked timing tho. ill do that as well. what is the ideal timing degree? i read somewhere that it was best set at a certain degree other than the amount recommended on the hem label??

Yeah, definitely check your timing and check for codes. The thing's not going to get great MPG, but you should be able to extend that range. I get to 200 and fill up just because. I've only set the gas light off once and I was around 220 I think.

Base timing is 10 degrees BTDC, but honestly, you can go well beyond that. I'm at 14 and that's where MY truck performs best. It's a little bit of trial and error for each case.

 

[Jt2El46]

I find that they like 10 to 12 BTDC. there a re several upgrades for the original injectors. I usually take a sample of the vacuum lines to the local parts store and buy bulk. about 6 ft of the 1/8" 3 feet of the 1/4" and 1 ft of fuel line for the return line. it usually cost around $25. The belt is not usually a problem unless someone has recently changed it, then the crank pulley is usually 1 tooth off. However the passenger side wires get misrouted a lot or the more common is not getting the middle wire to mechanically lock onto the plug properly because of the angle or the wire routing behind the EGR valve can burn a wire through.

 

[sportinh2o]

Just for grins, have you performed a compression test? I was chasing rough idle and poor mileage at one time on mine. It was early signs of my failing head gasket.

 

[10ac]

Just for grins, have you performed a compression test? I was chasing rough idle and poor mileage at one time on mine. It was early signs of my failing head gasket.

havent done that. i should just to see how compression is. is there a link or do you know the specifications of what the compression should be?

 

[10ac]

I find that they like 10 to 12 BTDC. there a re several upgrades for the original injectors. I usually take a sample of the vacuum lines to the local parts store and buy bulk. about 6 ft of the 1/8" 3 feet of the 1/4" and 1 ft of fuel line for the return line. it usually cost around $25. The belt is not usually a problem unless someone has recently changed it, then the crank pulley is usually 1 tooth off. However the passenger side wires get misrouted a lot or the more common is not getting the middle wire to mechanically lock onto the plug properly because of the angle or the wire routing behind the EGR valve can burn a wire through.

i just did the the wires and plugs and cap and rotor. everything good there and i made sure everything snapped good. ill check that vac hose out at my local parts store. thanks.
what injectors are being used? any link?

 

[Jt2El46]

RC Engineering : RC Fuel Injectors : Highflowfuel.com

 

[sportinh2o]

havent done that. i should just to see how compression is. is there a link or do you know the specifications of what the compression should be?

From what I just looked up, 150 and below is indicative of issues. From what all you have done thus far, I'd want to know just to help protect the investment. If the test shows an issue, you know where to spend your hard earned dolars.

 

[sportinh2o]

One other thing I have had was an air leak in the air intake plenum. Old, cracked intake plenum sucked air and the idle was off and performance suffered.