ps2cho

So since replacing my injectors a few months back it really cleared up 90% of my rough idle...but I am still stuck with **** poor mpg on my 300te wagon. Filled up yesterday and got 11.8mpg. I checked odo with gps and it checks out.

What part of the fuel system on the m103 would you suspect could be causing this massive overfueling? I have no vacuum leaks. Think distributor could be the culprit even if fuel pressures check out to spec on it?

rivcal4life

O2 Sensor is a likely culprit. When's the last time it was replaced?

YNVDIZW124

Did you adjust your transmission and accel linkage? Bad idle control valve maybe?

ps2cho

Yeh I had it replaced like 10k miles ago. It didn't change anything after I replaced it.

It has been adjusted.

Could it be possible that the ICV could be getting stuck open? The economy vacuum gauge which reads pressure at the intake manifold moves around at idle (and sometimes with rpm's too, but not exclusively). Maybe I should look into that? I've cleaned it out, so I can rule that easy fix off.

epowers777

I believe its ur ignition system.As you know Im selling my 300e I took off my ngk wires and my nology plugs and put it on the wagon. I was getting 25 mpg . My fuel milage went down hill. My car idles smoothe but not as smoothe as the nology plugs. Nology plugs are non resistor plug and give off a spark twice the size as bosch. I would also test your coil. What does the tip of ur plugs look like thatll tell you if ur running rich or lean. hope you figure it out.

bigdogbitu

My mpg suffered and I smelled gas too! Turned out the rubber fuel line from the fuel filter to the metal fuel line was leaking badly. It was cracked and fuel was leaking enough to form a puddle under the car. 1989 300E. $20 fix.

ps2cho

There are no puddles under my car, and there are no visual leaks, nor any gas smells, so we can rule that off.
I swapped the coil with one from the junkyard when I bought the car about 4 years ago...so I guess it could be a possibility.
I will for sure check out the Nology plugs, but I don't think that is the real problem. OEM Bosch should not be giving me 11.8MPG. I have something else going on.
I haven't pulled my plugs since I rebuilt the head, so I'll check that out as well and report back.

rivcal4life

Also, just a thought, listen to your cat. Actually, give it a good bump with your fist. At one point, the cat on my 300e had broken up on the inside which gave a telltale rattling sound when I hit it. Ive heard of those pieces plugging the exit hole on the cat, ruining exhaust flow and possibly killing MPG.

ps2cho

I actually have a brand new Magnaflow cat. The moron who did it though only hollowed out ONE of my precats. The other one is still intact . I'm struggling to find another exhaust shop who will hollow the other one out for me. One guy told me $600 to do it. I just laughed and walked away. Could one single blocked precat ruin my mpg? Maybe I should get that done first before checking anything else out.
He didn't do the back one...must have thought I'd never know cos its hard to reach. Of course when I pulled the head I looked and went god dammit.

epowers777

Did not think of that! That is a possibility. Do it urself we used a drill hammer bar and flex extention for my friend to do his cat. Again look at ur plugs that will tell you a story of whats going on.

epowers777

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

bigdogbitu

Nice link!

epowers777

Any info?

ds190

Anyone remember what fuel mileage we could be getting on our TE's? I get 16-18 city and 19-21 highway.

EDIT: answer to my own question- I forget about "the google"

http://www.fueleconomy.gov/Feg/noframes/8080.shtml

ps2cho

Well before doing anything else, I am going to get the other precat hollowed out. Gotta wait a few weeks as I am gonna get my dad to take the exhaust to work.

That and I found my suspension problem on my 260E to be the strut mount...so I gotta change it ASAP because its cracked. Some level of danger and also possible to dent the hood. So strut mount is #1 priority right now.

ps2cho

Well I have some good news!! I think I found part of the problem. I first swapped the EHA out and suddenly the next tank was 16MPG. No change in route. I do the same # of days at work each week and school. Next I adjusted the throttle linkage and filled up yesterday and got 17.9MPG. I've NEVER got 17.9mpg before!

I think the remaining has gotta be my fuel distrib, alignment (rear control arms replace first) and the 1 precat that is not hollowed out.

Glad to see a change for once in a while...

I swapped the EHA that was on the wagon to the 260E...so it will be interesting to see if the bad mpg moves onto the 260E?

epowers777

Do you have an egr on the wagon like mine?

ps2cho

Nope. I do not! I think EGR was 90+

epowers777

Well scratch what I was gonna say!! When I get all info together Im gonna post on your m103 link.

ps2cho

Wanted to confirm on the amazing boost in MPG. I got 20.5mpg in my last run. That was 75% freeway..but none the less a SIGNIFICANT improvement. Before with that I would have got... maybe 15mpg if I was lucky.

The low fuel light would come on around 220miles. Now I'm running close to 310miles before it kicks in. Huge difference. I still think I could be getting a couple more....I need to research the CORRECT way to PROPERLY test EHA. It's obvious fuel pressure =/= a properly configured EHA as I found out with my 260E.

appatula

Let us know for sure! I know for a fact that my EHA has been tampered with and would love to be able to test it out. Maybe a clamp on ammeter or mod the harness to pop an ammeter in series. Might serve as a crude way to find out current readings?