1995 Chevy Tahoe 4X4 - Adventure Rig Build

[edlaffoon]

It's good that you came around, I've never seen another like this and it would be a shame to unload it.

And thanks for making me feel better about my mileage

 

[Chevrolado]

It's good that you came around, I've never seen another like this and it would be a shame to unload it.

And thanks for making me feel better about my mileage

haha! Glad I could help you feel better about yours too.

And yeah.. even though the thing is pretty rough right now, I really want to hang on to it. It's clean. It's fresh. It's had a lot of time and money put into it. I just have to polish out the hiccups now.. hah.

 

[Larry]

Wow that is a drag on the fuel mileage. That is like the mileage a poorly tuned carbureted big block would get with a TH400 transmission and fulltime 4wd while dragging a broken F150 Ecoboom behind it. Are you sure the speedo is accurate to compensate for those bigger tires? Are you getting any check engine lights? Even an occasional blinking check engine light but not an actual solid light? You might also want to hook up a scan tool when the engine is warm to see if it is actually going into closed loop. Maybe it is running around in open loop all the time which will definitely affect performance and fuel economy. I've seen TBI rigs stay in open loop and never set a check engine light before due to a lazy 02 sensor or coolant temp sensor issues. If you have a restricted catalytic converter could also hamper your fuel economy but you should notice the engine being down on power. You mentioned the loose header bolts, loose and broken bolts can often be tied to restricted cats. Then again, header bolts like to work loose regardless. That is just the way they are. I hate headers and don't run them for that reason.

You say the truck won't coast very well when you let off the throttle? Does it seem to coast easier when the trans is shifted in neutral? If not, this could be something as simple as the brakes dragging from sitting for a while.

Don't give up on her. It takes times to work out the bugs sometime. Hell, I am still sorting out little drivability bugs on my FIL's '93 Sportside after its 4.3L to 7.4L swaperoo that I did last year. I think I finally found a good tuner to burn me a proper PROM to make this thing run right. We'll see.....It seems every ECM/PROM tuner you meet claims they are better than the last guy. LOL

 

[Chevrolado]

Wow that is a drag on the fuel mileage. That is like the mileage a poorly tuned carbureted big block would get with a TH400 transmission and fulltime 4wd while dragging a broken F150 Ecoboom behind it. Are you sure the speedo is accurate to compensate for those bigger tires? Are you getting any check engine lights? Even an occasional blinking check engine light but not an actual solid light? You might also want to hook up a scan tool when the engine is warm to see if it is actually going into closed loop. Maybe it is running around in open loop all the time which will definitely affect performance and fuel economy. I've seen TBI rigs stay in open loop and never set a check engine light before due to a lazy 02 sensor or coolant temp sensor issues. If you have a restricted catalytic converter could also hamper your fuel economy but you should notice the engine being down on power. You mentioned the loose header bolts, loose and broken bolts can often be tied to restricted cats. Then again, header bolts like to work loose regardless. That is just the way they are. I hate headers and don't run them for that reason.

You say the truck won't coast very well when you let off the throttle? Does it seem to coast easier when the trans is shifted in neutral? If not, this could be something as simple as the brakes dragging from sitting for a while.

Don't give up on her. It takes times to work out the bugs sometime. Hell, I am still sorting out little drivability bugs on my FIL's '93 Sportside after its 4.3L to 7.4L swaperoo that I did last year. I think I finally found a good tuner to burn me a proper PROM to make this thing run right. We'll see.....It seems every ECM/PROM tuner you meet claims they are better than the last guy. LOL

Thanks for the insight Larry. To answer your responses:
- The speedo is accurate (according to the police scanner things that tell you how fast your driving when you pass by them on the side of the road). I've driven past a couple and its always accurate. The tires I have are only 265/75's.. I think stock for these things is like 245/75 or something, right? They aren't too much bigger.
- I had the Coolant Temp (high) code thrown a few weeks back, and then it died the very next day after the code was thrown. Once I replaced the Coolant Temp Sensor with an AC Delco one, it then started running again and has been running since.
- O2 sensor is a brand new as of 8/31 when I replaced the thing after I got it all running right again.
- The power doesn't seem down to me, however, I really have no idea how it SHOULD feel. I bought the truck and only drove it for a few weeks when it had issues already going. I've been chasing issues since I bought it.
- As for the coasting thing.. it does coast when I let off the throttle. What I was trying to say about that is from a stop, when I'm on the brake pedal, and then I let off the brake pedal to gas it (an automatic trans vehicle will normally start rolling forward, right?). The Tahoe DOES roll a little, but not too much. If I'm on the slightest of hills, it will just sit until I gas it. Initially I was thinking that just from possible low air levels in my tires (because they tend to loose air and I don't have direct access to an air compressor to make sure my air is always in proper place.
I have not actually checked anything with brakes since Ive owned this thing. I dont FEEL anything as if it's dragging at all, and during braking its not pulling one way or the other, no shuttering, no signs of any foul play in the braking system. But I suppose its possible.

I dont want to give up on her. It's just tough to deal with chasing problems/bugs in your sole vehicle that you have to rely on to get you back and forth to work every day.

Again, thank you so much for the continual responses and lending insight for me to chase this. I love the vehicle. I just want to get it into prime condition now so I can have some REAL fun enjoying the thing instead of driving it paranoid everyday. hah. :smiley_drive:

 

[Chevrolado]

On a side note.. went through all my paperwork today and got everything organized into the glove box to make sure I will be fine when the time comes to get my CA SMOG check next year. hah.
Have my stickers ready to go into the engine bay as well for the visual inspection.

Good ol California emission control. :ylsmoke:

 

[Chevrolado]

Hey Larry (or anyone else if you happen to know as well).. does this hissing sound you hear in this video sound unusually loud to you? It does to me. I suppose it could just be the injectors goin within the intake.. but it sounds overly loud to me and I'm wondering if I should dig in deeper to try and figure out what it is and if it could possibly be the source of my rough idle/terrible gas mileage?

https://www.flickr.com/gp/chevrolado/8A36y0

 

[Chevrolado]

Little update.. This weekend I drained all of the break-in oil from the pan. Pulled the filter off the block and unbolted the adapter that was on it. I bolted up the original oil cooling hardware and ran the lines up to the radiator as factory spec was. Refilled with some Castrol Syntec Blend motor oil and got it back on the road.

So far, it feels like it runs much smoother on acceleration. It feels like it doesn't have to try as hard to move. Easier on the take off. I'm hoping this will definitely bump the MPG consumption a little bit. Hoping to see double digits! hah. I have a couple more weeks of things to play with and then I'll be taking it for a freeway trip out to Palm Springs.. so that'll be a nice test to see what highway consumption will be.

 

[Larry]

Hey Larry (or anyone else if you happen to know as well).. does this hissing sound you hear in this video sound unusually loud to you? It does to me. I suppose it could just be the injectors goin within the intake.. but it sounds overly loud to me and I'm wondering if I should dig in deeper to try and figure out what it is and if it could possibly be the source of my rough idle/terrible gas mileage?

http://www.flickr.com/photos/chevrolado/10046601246/

Sorry, late to the party on this one. Yes, that video sure sounds like something is leaking back there. The TBI injectors make a digital clicking noise, not so much a hiss noise. Have you narrowed down the source of the vacuum leak since you posted this on 10-1? If not, start spraying some carb cleaner in that area and you should notice the idle speed change once you spray the over the vacuum leak source. Just be careful you don’t spray too much near the distributor cap or you might singe your eyebrows. I would suspect that throttle body spacer or one of those vinyl molded vacuum hoses could have a crack in it. A vacuum leak will cause a horrible idle amongst other things. As loud as it sounds on video, you might be able to feel the vacuum leak with your fingers and not even have to use carb cleaner.

 

[Chevrolado]

Thanks for the input Larry! I'm getting multiple people saying vacuum leak, so Im really leaning that way. I personally think the idle is rougher than it SHOULD be. So I'm going to go ahead and just cast my vote that there is a vacuum leak somewhere and I really need to find it.

Thanks for the help.

 

[Chevrolado]

So... little update on this whole mess of a Tahoe.. Larry, like you guessed it. Major vacuum leak. And yep.. once we found out where this one was, you DEFINITELY dont need any carb cleaner to find it. Just your fingers...

http://youtu.be/9RyzLy2ZbLQ



So, now the intake will need to come off and all that will have to be re-done...

 

[Larry]

Dude! Well, heck from THAT video it looks like you have a major intake leak at the exhaust crossover. Once you get that dealo addressed you should notice a big difference and hopefully be good to go but don’t stop there as the previous video sounded like an actual vacuum leak at the rear of the engine. That is the sucktastic part about the old generation of GM engines with wet intakes where you have to drain the coolant in order to remove and replace the intake manifold gaskets.

Ah, well…that kind of work builds character of a 1960’s hot rodder type guy

.

For what is worth, your video almost sounds like a cylinder head with an exhaust crossover mated to an intake head without an exhaust crossover. From the looks of the intake bolts you are using a 1996 and later Vortec head, right? When you pull the intake off make sure you are not dead heading the cylinder head exhaust crossover to a flat intake port at the intake. Hard to explain but it will be obvious once you remove the intake. If the ports don’t line up…that is a problem

This head has an exhaust crossover..

This head DOES not have an exhaust crossover….

Does your cylinder heads have a center exhaust crossover? Does the intake have provisions?

If you bolt a head with an exhaust crossover to an intake without one you will get a huge leak. I'm not even sure that is a possibly on a small block but from my experiance that is a boltable possiblity on a big block. My experiance lies more with big blocks than small blocks so I am not sure if the intake/head exhaust crossover mixmatch is even possible on a small block but still worth looking at?

 

[chilliwak]

WOW:Wow1: now thats what i call a vacum leak!!!!:Wow1:

 

[rabbiporkchop]

My bumper and tire carrier was made by EMS Offroad.

 

[Chevrolado]

Larry, thanks for the info on the heads man!

My heads are the Edelbrock 60859 heads. http://www.summitracing.com/parts/edl-60859
Which do not have the crossover you are talking about.

In fact, these are a shot I took during the motor build process.. and I dont see the port you are showing on the one with the crossover:

It should be all Pre-Vortec. If all the parts that I got are truly the parts that I ordered.
I knew the standard 95 computer wouldn't do well with the vortec style heads so I kept all my parts search for everything that would work up to 1995.



rabbiPorkchop; thanks for the shot on the rear bumper. I wonder if that type of setup would work for my barn doors.. I like it. Do you recall how much they cost from that company?

Thanks.

 

[Larry]

Larry, thanks for the info on the heads man!

My heads are the Edelbrock 60859 heads. http://www.summitracing.com/parts/edl-60859
Which do not have the crossover you are talking about.

Good deal, sound like just a poor sealing intake gasket for some reason. That should be an easy fix.