Falls here the 23rd so its time to get the 2000 bravada up and running 100% for Michigan winter. I am currently only getting 11mpg and drinking gas like crazy. I've replaced the spider injectors, cleaned MAF, EGR, Throttle Body, tune up w/ac delco plugs and duralast wires. I currently do not have any codes the only lights on are the AWD (leaking fluid at transfercase refill?) and ABS light (front passenger speed sensor).

I did have a high idle code at one point after cleaning the throttle body and EGR. After cleaning these I got the multiple misfire code as well and it started to run very rough, eat gas, and trigger multiple cylinder misfire. Then i replaced the spider injector system which did fix the misfire code but still drinking way more than it should. When I first purchased the vehicle I was getting around 300miles per tank.

Was i supposed to gap the plugs when i did the tune up? If so wouldn't it trigger engine light?

I need to fix this asap otherwise it will be a very expensive winter.\\


Thanks!

 

Definitely need to make sure the plugs are gapped correctly.

Duralast wires? Not saying they are the problem, here, but they dont even last long on Fords and Fords are far less picky on what will run and not.

You need to drive it with a scanner and make sure the system is going into closed loop operation, that is where the ECM looks at the O2 sensors to trim the mixture. If you have a bad Engine Coolant Temp sensor {ECT} it may not be getting to closed loop.
You want to shotgun it and replace that, okay.. but then what if it doesnt fix it?

You MIGHT also have a stuck open thermostat.. is the gauge reading in normal range?

 

During the summer when i drove it on rare occasions it would sit about half way(210) until i put the air on then it ran hot to about 225-230 on idle at stop

Last night i took it for a spin (first time in a month hoping the problem would solve itself ) and it got to about i think 160-170 (three notches below 210) and sat there. It was cool outside about 45-50 degrees. I've owned this thing since the spring.

 

4.3's have a 195° thermostat. If that operating temp isn't reached, it wont run correctly. The computer will tell the engine to idle faster and run richer to try and get to 195. This is more apparent in colder weather.

 

Just ran to Lowe's with my pup and engine light popped on. Got it scanned and retrieved

P507 (Idle Air Control System RPM Higher Than Expected)
and
P1870 Transmission slippage detected

I also took a pic of my temp gauge at idle after running my errands..

 

Like pettyfrog said, you need to run it with with a scanner and that will give you what the Engine Temp is. Like was said earlier, needs to run at about 195 for it to run right. That is one of the good things about these, if the thermostat is going bad, then generally fail open, and are easy to replace.

As for the codes, can you not tighten the plugs any more to get them to stop leaking? I know that sounds silly, but hey, ya never know. Once you've got the plug tightened a little more (if possible) make sure the fluid is good and top of if necessary

To take care of the IAC code, you can take the IAC valve out/off and clean it, which may take care of that problem. It is a pretty easy clean.

 

^^ what they said.

For the P1870 search around the forum. It's a common problem relating to the valve body in the trans.

 

Forgot to mention I already cleaned the IAC valve and I also replaced the MAP sensor. Would the scanner at autozone be able to tell the temp?

Also if i replaced the spider injectors myself would I be able to replace the valve body in the trans or is it harder? I've never dropped a trans before but always could give it a shot

 

Need to establish temp is right
then
Check for vacuum leaks causing high idle
Warm engine
Disconnect the IAC connector.
*If necessary shim the throttle stop to keep engine running*
Remove all vac lines and plug the port{s} - does idle change?
Use unlit propane torch around upper manifold gaskets to see if engine speed changes.

 

Valve body can be done with the trans in the vehicle. Drop the pan, pull the filter, unhook the wiring harness, unbolt and remove valve body.....there's plenty of info around the web about it. I chose to have a shop do it but that's more because i don't like the mess the trans makes all over everything you touch LOL.

This may be (and probably is) totally unrelated to your issue, my blazer has been slightly down on power and getting like 13 mpg lately. I've changed the lower intake manifold gasket etc. no problems starting or rough idle or anything. Here the CAT is clogged and one of the honeycombs blew apart in it. Wasn't enough to throw a check engine code but it's definately done.