TOPIC: Modification to 96 3 cylinder Metro

I had submitted a modification report earlier on grooving the little 3 cylinder Metro. Drove about 250 miles after doing the mod, with a mpg of around 57. Since then, the mpg has slowly declined to the point where it's about what it was pre-mod: 42-44 mpg on the highway. Other modifications:
1. Put an extension on the one oxygen sensor, pulling it out of the exhaust stream, 2. Left the PVC valve alone, since the hose entered the air intake before the air cleaner, 3. Blocked the EGR system, capping the vacuum tube into the throttle body with a vacuum cap.

Reasoned that it was still getting signals to input too much gas from the ECU, probably from the MAP. No MAF on this system, just a MAP, activated by a vacuum tube from the throttle body.

Recently installed a MAP enhancer--the potentiometer with a variable knob, so that I could reduce the voltage coming from the MAP senser to the ECU. Even just a little reduction made the engine run smoother, with better mpg (according to my Scan II. Seems to have the most effect when cruising or coasting, when accelerating, not much difference. Have yet to be able to take it out on the road for an extensive mpg test (too much snow).

Will report that when done. And also results from HHO generator, when that's installed. Am most curious to see if that makes a significant difference!

One thing you must remember is the winter fuel mix more alcohol in the gas this will cause it to drop mpg. Before you do any major changes I recommend check fuel trims. If you run hho your gonna have to modify several components as the extra oxy. will dump fuel. See if your fuel trims are neg this car will run long = neg8 short bouncing around neg 0 to 5 Everyone must keep in mind that after grooving we are also lowering the temps of the engine and when its really cold the mpg will take longer to build up as the Iac and the Ect will show colder meaning richer mix .If you are going to manipulate anything these two are very important. If you have away please post fuel trims Idle and at 65mpg this will give us an indication whats going on. This could possibly save you alot of time. Dan gadgetman Mo.

Confused about one thing, need education on the other (or both). 1. When you say "the winter fuel mix more alcohol in the gas" do you mean there's alcohol in the gas that comes out of the pump? 2. Or alcohol in the HHO electrolyte to prevent freezing? Need to be educated about "fuel trims." I've seen this term a number of times, but don't know what it is or how to ascertain. Can you point me to some literature to learn about it-and what kind of instrument I need to measure it?

Yes, The alcohol is in the pump more in the winter. The other, an automotive scan gauge like autozone or Orielys sells just so it will read the fuel trims, the fuel trims let you know wether the ecu computer is adding or taking away the fuel to the injectors neg means taking away pos means adding. The long term starts at 0 when reset thats what they were saying, the short term teachs the long term as this becomes, lets call it the memory bank. 0 when reset is a fuel ratio of about 14.7 to 1 fuel ratio this is the standards that our great govt and the car manufactures and oil co set years ago. The fuel trims are measured in percents meaning add long and short together and say neg 2 plus neg8 = 10 percent of the raw fuel is being taken away. If you want to call me I can verbally explain it better, my no. is on the find a gadgetman website. Dan gadgetman Mo.

Thanks so much, Dan for your replies. Am now clear on Fuel Trim. Have a Scangauge II, and reading the manual have just figured out how to use the X-Gauge feature to access fuel trim figures, using the data available on the Scangauge website. Will report on findings (when it stops snowing here in central Washington!). And I sure didn't know that alcohol is added to gas at the pump in cold weather!

Check for the PCV valve answers.com says: "The PCV Valve is located in between the valve cover and the air cleaner. There is a vacuum hose that connects to the top of it. You will need to remove the air cleaner first and then remove the vacuum hose. Once the hose is removed you will need to remove 1 screw from the small bracket that is holding down the PCV Valve. Be careful and try not to messup the head of the screw, as the material that the screw is made up of is quite soft. So use a screw driver that fits the head."

When you find it, plug the vacuum hose where it connects to its source (intake or TB). I recommend that the EGR is reconnected as we don't want the mess with emissions. We are not with the PCV as it is connected to the air cleaner. Vacuum is a huge leak. Let us know the results, I think you'll be pleased.

Peter,

Where in Central Washington?

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

Hello Karl,

I live in Ellensburg, recently retired from CWU. However, I have a daughter who lives with her family quite near you, on N. 39th, near Orchard. Would like to meet sometime when I'm over there.
Funny story: couple of months ago her husband rear ended another car, is mechanically helpless, so I took his car (a 95 Camry-still drivable) home, pulled out the radiator frame and such with a chain and tree, aligned the hood latches and installed new headlight assemblies--and as long as I had it for week, did the groove. This was much against his wishes, as he told my daughter "don't let you dad do any of his crackpot things to my car!" He still doesn't know, if he knew, he wouldn't have accepted the car back, says my daughter. Don't feel too guilty about it though, as I had purchased this car for my daughter some four years ago, before they were married. His PVC valve was completely plugged, so I just left it, and didn't do anything else, as it might have been visibly noticeable. The inside of the throttle body was unbelievably coated with carbon-cleaned it out. On the 110 mile drive back to Tacoma with the cruise control at 65 mph, the car got 40 mpg, at least 12 more than ever before.

Sounds like a good deal, he's still clueless, eh.

Yep, I'm on N 26th just off of Orchard, very close indeed.


Would be good to meet and chat with you.

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

Thanks, Dan and Nick, for your suggestions.

Regarding the PVC valve on the little Metro: there's only one breather tube from the valve cover, which T's off, one arm going straight back to the air cleaner housing, one arm going down to the PVC valve. I turned the T around, blocked off the end going down to the PVC valve, then, leaving the PVC valve in place, plugged it by fitting a vacuum cap over the opening. Noticed an immediate increase in engine efficiency.

I had previously installed a PVC "enhancer" in the hose leading to the air cleaner, an air compressor filter with a few marbles in it to help condense the water. This worked fine (but didn't on several other vehicles, as it increased the pressure in the crankcase to where it forced oil out)--collected much water and crud. I think it worked OK on the Metro because the PVC valve (which was not in the the filter loop, allowed the release of the pressure. But with the PVC valve no longer operative, oil began to be forced out the oil cap, so I removed the filter. Sure wish there was a way to utilize a filter though, I really liked the concept of removing water and crud from the blowby gasses before going back into the intake system.

Also tried two other things:

Installed an HHO system from the Mileage Shop, and used their recommended means of re-educating the ECU to account for the difference in the Oxygen (described in a previous post), and removed the oxygen sensor extender.

Installed a MAP enhancer--enables variable manual control of the voltage going from the MAP sensor to the ECU. Pretty neat to watch (on a Scan Gauge) the MPG climb as I lean out the fuel. Also found that different driving situations require different settings: driving uphill requires almost no lean; coasting down hill I can lean it out to where the MPG reaches over 900 MPG, though it chances stalling the engine; driving on the level I can lean it to where the MPG is over 60, at 60 MPH.

Seems to work well. Took a 70 mile round trip with an hour wait between trips. The return trip seemed to have even better results than the out trip, but averaged 57.7 MPG with everything working. Of course, I need to check that against the actual fuel usage at the pump for accuracy--still have yet to do that. Will be taking a 700 mile round trip this weekend, will be curious to see if results remain, wax or wane. Will post.

Set the Scan Gauge to read fuel trims at S and L, but still mystified at how to read the results. Though the readings vary depending on the driving situations, the L is always less than the S. At a steady 60 MPH on the level, S is at 20, L is at 0. ???

Hi Peter
There is a product on the market called condensator, look up .
I have own a condensator unit it works very well, it takes out carbon and water of the airstream going through from pcv value.

My phone# 519-638-5921 give me a call if you have any questions.

Thanks Aaron

Hello Aaron,

Thanks for the tip on the Condensator--sounds just like what I'm looking for--a way to clean up the blow by crap before re-entering the combustion chamber. Explored the website, looks good, though the cost is a little steep (at least compared to an air compressor filter), though a well engineered item is no doubt worth the cost.

PeterG