Multiple problems 7M-GE
 

I recently returned from a deployment and pulled my car out of storage.

I started it up and it ran just fine (with the exception of a rough idle) right up until it got warmed up completely.

i have massive power loss, the exhaust turned beat red from cat #2 back to the muffler, and it is having serious idle issues.

I drropped the cat thinking that was a problem but it was in perfect condition.

I tried timing it but i cant get it into perfect time, i am not sure if im missing something here but i set it TDC and hit it with a timing gun get really close but every few times around the notch jumps and comes back. What could cause this and is the timing issue causing the problem with the exhaust?

When timing it did you remember to set the diagnostic jumper? Have you tried dropping the #2 cat and the piping behind it and running the engine? Any difference? How long has it been sitting? Have you added any fresh fuel or gasoline stabilizer?

Here are the details on setting the timing: http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=18

Yes I did jump it, a friend of mine has a diagnostic tool with a timing setting do you think that might help?

Dropped #2 cat and started car still ran rough, loud as hell and actually a quite pleasing sound, then after about 5 minutes it died.

It was sitting for about 6 months and I added 2 gallons of gas and fuel treatment when I picked it up but thats it. do you think adding more fresh fuel would help?
And if that doesnt work what else could it be?

Fresh fuel is always the first thing wo start with when coming back to a stored vehicle. Are there any diagnostic codes stored in the ECU? No, no diagnostic tool does much of anything with these cars except for a certain advanced diagnostic tool which Toyota used to make... only available through them for a few grand, naturally; You can find out just as much with a piece of wire and a multimeter.... and a book. Some tools come with adapters for this type of system but their results are usually so far off and so bizarre I really wonder where they got their info.

No codes are popping thats whats driving me insane!

Purge the old fuel and put in a couple gallons of 89 octane. Run that for a bit and see if it starts to clear up.

Hey...im a pretty cheap guy when it comes to gas...so i run up 87 at the pump with 10% ethanol...i havent seen anywhere else that doesnt say 10%...anyways...its always bogged and the timing setting was at about 12 degrees Advanced from TDC...thats when i got the car...I advanced it to about 16 degrees cuz im a noob at this kind of stuff and i guess i got the gear on wrong for the distributor and could only retard it to about 15 degrees...anyways the car ran pretty darn good...burnin rubber and stuff.

A few days ago i decided that i should try and put the distributor on right and the timing back to 10 degrees like the manual says. and its back to bogging at the lower rpms at the factory settings. So a few days of bogging and I decide that maybe the crank marking is wrong and I rather want it to run like before, so as im going through the process of adjusting the distributor gear to advance it a bit...some dude comes out and ask me about my supra. To make a long story short, he had the same problem and it cleared right up when he changed to buying the 92 gas for fuel. and to be honest, i did what he said, ran the gas out...then filled it with 92, and the car seems to run better.

My questions are: Is the 7mge meant to run 92 only? What about the stuff i mentioned earlier about running at 15 degrees plus advanced, and running fine with 87? I happen to get free gas :) but only 87...thats why im asking. Thanks for reading through and any helpful comments are much apreciated.

The GE is actually spec'd for higher octane than the GTE... So 87 for the GTE and 91 for the GE or around there... altitude, ambient air temp and humidity all play a part in determining what octane is best for your situation. I ran 87 in my GE but only because I'm a mile above sea level and the air is thinner. The difference in price between mid grade and high grade (when it's not free of course) is only a couple dollars per full tank... it's cheap insurance. BUT, also to keep in mind is that the higher the octane the less power it makes per unit.

Advancing the ignition timing (the spark advance, not the same as the mechanical timing) accomplishes very little. The ECU will push the timing as far forward as its ignition maps allow... this is allot further than the 6? you've advanced it... and once it detects knock it'll retard it until the knock is gone. There will be a bit of a difference when the car is cold and running in open loop (not the time when you want to push the engine too hard), but once up to temp it's back in the ECU's hands.

The ECU adjusts timing for knock and ping, but knock due to detonation isn't something that adjusting timing is going to help with... the fuel is exploding versus burning at a predictable rate and in a predictable pattern.

My recommendations to you are to use come Mopar combustion chamber cleaner to get the pistons and valves nice and clean and then to use a GOOD octane booster. I'm assuming you've got plenty of humid, but I know you've got plenty of heat too. Also, get the mechanical timing sorted out and get the ignition timing in check; It should be 10? BTDC.



EDIT: I should mention that fuel octane grades vary by region.... here we have 85 as the lowest, 87 mid and 91 high... this is M+R/2, there are a couple different standards for rating octane, the US uses the two methods averaged. I know in some places in the US 87 is the lowest and 93 or 94 is the highest with 89 in the middle; This is generally in the higher temp and drier climates.

Thanks for the info! So check mechanical timing too? so the distributor timing advance does nothing that the ecu cant adjust...so, why do you think it ran better when I had it at 16 degrees advanced? Also about the octane booster...87 plus..lets say a good octane booster...that will be sufficient for fuel? I gotta take advantage of my free 87 gas situation :p . As for cleaning out the pistons and stuff...I did what nickleeye suggested in a post...used some carb cleaner into a vacuum and just ran it a bit. seems to work.
Im at sea lvl, 60% plus RH, and a heck a lot of heat...sucks to be in hawaii right now. Im practically in a sauna over here. The timing is set back to 10 degrees. But i havent fully experimented with running the 92 gas yet.

Everything you're saying here makes me think the timing is off... either the mechanical timing is off or you're not properly setting the ignition timing. It's also possible that you are squeezing a little more power out of it but not safely... Don't run at any significant advance without higher octane fuel, it's begging for a rebuild. Yes, the ECU tries to pull ignition advance if knock is present, but it can only ever pull or add so much, you're shortening the systems safety net.


If you want to stick with your free fuel you gotta be willing to toss in $10 of toluene with each tank. Remember, the octane booster ALWAYS goes in the tank BEFORE the fuel; That way it gets properly mixed in.


I prefer MCC, a bit nastier. For a thorough clean you may pull the spark plugs and spray in a good amount and let it sit overnight; Just spray in enough to fill the piston domes. Most of it should be evaporated by the next afternoon and it will be hard to start after you put the plugs back in.

thanks for info above! Just substituted lucas cleaner with the MCC aparently cant buy this outside of stealership.

I get code 51 once every other time i run the car...seems to me like the connector looks loose...The only code i get is 51...til i wiggle the connector around and it goes away...will this cause significant powerloss and timing problems? I also noticed I have the turbo tps on my NA. 1987 7mge.

I checked the ignition timing and the mechanical timing and all of it looks good, marks match up, etc. When i first start the car the car runs great...idles fine in diagnostic mode...then suddenly idle will drop and my timing jumps around the 10 degree mark a little bit ( i got my gun out). Should i go get a NA tps? Its all stock except I slapped on a ponteza catback. I also took off the exhaust header to see if there was carbon build up somewhere...looks pretty darn clean. Car bogs and makes me cry when a civic rips past me on the freeway. Installing new magnaflow cat as of right now...damn rust sucks.

Newer Civics have no problem keeping up with the 7M-GE.... I mean 3500 lbs and only 140 to 160 HP at the wheels? C'mon....


Lucas is garbage, if you're going to run an in-tank fuel and chamber cleaner get something good: Techron, 44K, Redline SI-1.

And if I hear of anyone here ever using Lucas oil additives I'm going to BAN THEM!


Check your intake plumbing for leaks or cracks, replace the vacuum tubing, test the AFM. You can try running with the TPS unplugged and see if it drives better; If it does, replace it.

ok no lucas additives :p. What about the turbo tps on a NA? I got a civic myself as my daily and I know i can keep up with a NA supra...but not completely rip it up on the street...thats what my supra feels like...I know it can run faster than it is right now...bogging is making me fustrated...I also got silicone vacuum line replacements coming in...checked out the vacuum...reads 15 hg...kinda low i think.

But what i dont get...like i stated before...i was running at 15+ ignition advance...and it was running fast...but I toned it down to 10 degrees...and now its back to bogging.

The TPS really doesn't matter at all which model 7M it's from as long as the inner tabs are of the same alignment as the tabs on the throttle body. There was a change in the TB on 89' and up MKIII's where the TPS' and TB's actuator tabs were changed and are offset 90? from the pre89. I think the fins/tabs on the pre89 (both GTE and GE) were horizontal and on the 89+ N/A they were vertical... I don't know if the 89+ GTE changed though. If the tabs mate right up, you're fine (there's no difference in the internals); If they're off 90? it won't work.

5? may make a small difference but not much.. if you can really feel a big shift then something else probably needs attention.