Still no power under load MR2 

"RustedSprinter" (rustedsprinter) 07/13/2015 at 20:22 • Filed to: None

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Do you guys think that unplugging my AFM on my MR2 is a good way to test whether or not it works? I followed some advice you guys gave me and it works a little better. It can rev to 4K in first as soon as the car is on but once I shift to second it gets strangled. The Engine hits like a rev limit even when I’m flooring it. If I dont shift at 2K it dies. It revs fine in neutral and thanks to you guys the idle is smoother.

RustedSprinter > RustedSprinter 07/13/2015 at 20:29

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Also I now have a bunch of exhaust leaks.

Flavien Vidal > RustedSprinter 07/13/2015 at 20:31

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Maybe a mass air flow sensor going bad??

Thinking about it, it could also be some kind of dead catalyst?? Does it make weird noise around the catalyst when you drive? Other than the holes in the exhaust of course lol

But I think it’s a potential MAF problem...

TheOnelectronic > RustedSprinter 07/13/2015 at 20:32

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A lot of MR2 troubles today!

RustedSprinter > TheOnelectronic 07/13/2015 at 20:34

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Oh yeah! They never stop.

RustedSprinter > Flavien Vidal 07/13/2015 at 20:36

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I’ll have to pay more attention to that. Its hard to hear since my exhaust now has like 3 holes in it.

Flavien Vidal > RustedSprinter 07/13/2015 at 20:39

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If you have never payed attention to the Mass Air Flow sensor, then this is most likely your problem... Get it out, clean it up VERY well with a MAF cleaner special product you can find anywhere (if not, a basic electrical cleaner would do the trick), don’t touch the sensor itself though, it’s very fragile, plug it back in and you should be good to go...

If you see it’s still way to dirty looking after using the product on it, find a new one on eBay and I’m pretty sure you will be all good.

beardsbynelly - Rikerbeard > RustedSprinter 07/13/2015 at 20:40

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could be the TVIS valve not opening?
Timing?
plugs?
valve clearances?

could be one or a whole bunch of things.

here’s a link to a site where you can download the BGB (big green book) if you don’t already have it. It has a troubleshooting section that mentions the problem you’re having:

http://manual.teq.org/

RustedSprinter > beardsbynelly - Rikerbeard 07/13/2015 at 20:46

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Thanks for the link! The timing belt was replaced. I cleaned out the throttle body. Have to check the TVIS. Plugs are a bit old I should change them next. I’ll read up on that book.

beardsbynelly - Rikerbeard > RustedSprinter 07/13/2015 at 20:56

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the BGB is pretty much essential for an old AW11. I’d double check the timing if it was recently done, especially if this problem wasn’t around before the belt was changed.

DogonCrook > RustedSprinter 07/13/2015 at 20:58

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To check a cat just make sure it is hotter after the cat than before it.

Car should run without a maf. Don’t push it and listen for detonation but if the problem goes away that’s your problem. You may need to keep tapping the gas to keep it from dying.

Edit:,well that’s how you check one. This doesn’t sound like a maf issue. If your going so rich or lean the engine dies be very careful. Most cars go off manifold pressure, the only exception I know of is an rx8. The maf being completely removed won’t cause this.

RustedSprinter > DogonCrook 07/13/2015 at 21:08

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Thanks! I’ll try that.

DogonCrook > RustedSprinter 07/13/2015 at 21:12

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Does it backfire or pop when this happens or on deceleration? If you think you are going lean or don’t know find that out first. Putting a load on a lean engine will not end well.

RustedSprinter > DogonCrook 07/13/2015 at 21:18

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No back fire. No pop as far as I can tell either.

RustedSprinter > DogonCrook 07/13/2015 at 21:18

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Will unplugging the AFM cause it to go lean?

NonDriftingS13 > beardsbynelly - Rikerbeard 07/13/2015 at 21:24

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I second this. Could have jumped timing.

DogonCrook > RustedSprinter 07/13/2015 at 21:35

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I don’t really know your car, you’ll need to check a tuning forum and find out what your ecu uses as reference for timing and fuel maps. If it doesn’t know what to do it’ll revert to limp mode, but should throw a code and the check engine light. At that point though your engine doesn’t know if you have an air leak or a hung secondary air valve etc so you can still do some damage.

Pull a sparg plug and look up how to read them or post a pic here.

Highlander-Datsuns are Forever > RustedSprinter 07/13/2015 at 21:42

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So I had almost had the exact same problem on my Isuzu pickup. Turns out the Cat self imploded and plugged the exhaust. New exhaust and it ran perfect.

DogonCrook > RustedSprinter 07/13/2015 at 21:54

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A googled it and your ecu does use the afm until that works you are in limp mode.

I don’t know what issues you had before but a lot of people have issues with water around the electrical bits on your engine. Check around all your ignition components for even a hint of water. Especially around the coils and spark plugs. You should definitely join a Mr. 2 forum it’s honestly the best way to get to the bottom of a problem like this. If it’s happening to yours it’s happened to someone else.

RustedSprinter > DogonCrook 07/13/2015 at 21:58

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I didnt really notice any water. I’ll look harder tho. The car sits outside. I can still try unplugging the AFM right?

RustedSprinter > DogonCrook 07/13/2015 at 22:03

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I’m a member that the MR2 forums. Alot of the people that have my problem never check back to say “This worked!”

DogonCrook > RustedSprinter 07/13/2015 at 22:13

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Yeah, as the other rusty said it’ll go rich in theory. If it doesn’t it’s probably a massive vac leak. Since you haven’t done your plugs and wires in awhile I’d swap them because they need to be done anyway, and you can look for water, and you’ll get a read on how it’s actually running. It’s always what I do first. You can sometimes save yourself hours of trouble shooting just by knowing if you are rich or lean. You might get lucky and have some water in there.

DogonCrook > RustedSprinter 07/13/2015 at 22:22

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Lol yeah, but you can get an idea where to look. At the end of the day, it’s just eliminating the likely culprits one by one. While everything is open and the tools are out replace the cheap stuff and wear items in the area you are working on sometimes you get lucky. It’s hard to find weird issues like a bad injector seal but they are like 50 cents so just swap em when you are in the area etc. If something looks janky don’t wait it’s failure may not be obvious and take days to find even for someone with a lot of experience that knows the car inside and out.

RustedSprinter > DogonCrook 07/14/2015 at 17:13

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It was raining on and off today. So I didnt get much done. I just turned the car on and noticed that something directly below me shaking. I rev’d in neutral and did not hear any popping. I’m going to see if I get a code off my “diagnostic box”. There is no CEL on but maybe it stored codes from the computer.

DogonCrook > RustedSprinter 07/14/2015 at 17:55

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Looking at your old posts, when it would die when it was warm at idle, did it shut off or just sputter out? With your current issues does it just shut off or lose rpms till it dies? Does the exhaust smell real gassy when it’s warm at idle? What rpm does it idle at, or is it all over the place? And have you ever had any of the fuel system components replaced or looked at?

RustedSprinter > DogonCrook 07/14/2015 at 18:56

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I have not looked at the fuel system yet. Think since it had old gas and we ran the old gas thru that seafoam will help? It now has 1.5 gallons of 93 gas in it. Is that too low? I had to drive it 3 miles home from the shop and the shop did not fill the tank up. Idles normally around 1K. But today it was a it was at 1.5 ~ 2K maybe its because I started it in 1st gear some how. I havent smelled the exhaust yet. I’ll do that tomorrow. Before it would sputter and die in idle and then the battery would be drained cuz the alternator’s belt was snapping. I had it idle on friday for 20mins and it didnt die on me.

DogonCrook > RustedSprinter 07/14/2015 at 21:29

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Well I’d replace the fuel filter immediately, but every component needs to be checked. a clogged fuel filter could cause your problem without triggering the cel, and a fuel pump that is dying could as well. Seafoam could lead you to the problem, meaning if you run a bottle through and it gets better, you may be on the right track. Its definitely time to check your injectors and have them cleaned as preventative maintenance anyways. Replace the orings when you do this they are cheap and are a source of vac leaks when they get old. Seafoam works best diluted as little as possible and when everything is as warm as possible. It can sometimes do th trick but you’ll still want to check everything so you do not get stranded or have to hunt down issues in the future.

If it’s real rich it’s likely a fuel system issue, like leaky injectors, or your car has a cold start injector which may not be shutting off. If that’s the case it’s probably a bad coolant sensor or air in the coolant system. If the system is starving and running lean, it’s probably going to sputter, have some bucking, or backfires. Bad fuel pumps tend to just leave you with no power when they warm up the gas pedal becomes worthless. These are kinda general rules though things can fail in unfathomable ways so I’d just eliminate the entire system as the culprit as it’s all fairly cheap and easy.

If it’s just dying instantly, no sputter just cutting out, it’s probably electrical, go over your ignition system components one by one. If you don’t want to constantly check dwell and replace points in your distributor, consider a pertronix. They run about $100 and you won’t have to mess with it anymore. Make sure your distributor doesn’t have a lot of play in it by jiggling it. The distributor always needs to be in spec as far as timing and dwell and good contacts or you will be chasing your tail trying to find problems. The pertronix is well worth the money or get used to checking this often and first every time an issue pops up.

Vac leaks are a real pain to track down, as a rule make sure every hose has a clamp on each end and the hoses are cheap so replace anything questionable. Use carb cleaner to hunt down leaks but you won’t always find it that way. The idle will change when you spray in an are that has one. Vac leaks cause high idle, and idle hunting till they are fixed.

That’s all stuff you need to stay on top of anyways and it where I’d start. They could be your main issue or may not but it all needs to be eliminated and you’ll be able to cross off a lot of culprits. Plus when you do find your issue you’ll have a much better idea of where you stand as far as reliability is concerned and have a pretty good understanding of how all your systems work. This is tedious stuff, but it’s also why you need to stay on top of it all. None of its terribly expensive and when I buy a used car I do it all anyways so I know what’s good when a problem arises.

If I was going to focus on your main problem, it sounds to me like if it isn’t a fuel delivery issue, it’s part of the components that assist in warm up. An air valve isn’t closing or that warm up injector is staying on. There is a pretty radical change in how it runs cold vs warm, and your sensors aren’t triggering a cel. You can easily elimanate the 02 and afm by unplugging them but you usually get at least a pending code for stuff like that, but maybe not. Vac leaks usually are not that noticeable at high rpm though they do cause a high idle. Cutting power like that at high rpm makes me think if it is in the T-vis system and it is a massive one, because if it will kill the engine at that high an rpm that suddenly it would be obvious in a visual inspection. If the valve isn’t turning over it’s super rich because it isn’t getting enough air, but it will smell really gassy if you pull the spark plugs and they will definitely show you’ve been running rich. You need to eliminate they fuel system as the culprit first though.

If this is a car you will keep for a long time, and why not it’s a fun unique car, I’d consider a air fuel meter. It’s the best way to prevent serious damage if something is wrong before it’s catastrophic. You will be able to tell when things are getting out of whack before it’s a serious problem and the difference between a rebuild and a new engine is sometimes how long it takes you to notice a problem. I don’t trust temp sensors either, the stock ones are more or less on off checks, an oil temp gauge is a pretty good investment as well.

Be methodical and test everything system by system. This process will be so much easier next time, and hopefully next time once you have a good foundation you can start adding some go fast bits. If you are going to ditch it, you’ll get more money if you’ve got receipts, a clean looking bay and good looking rubber, a smart buyer will know what he’s in for if you can’t tell them when the last time a fuel filter or the points have been changed so it’s well worth it.

If none of that helps, you’ll at least be able to take everything you now know and someone who really knows your car can use that info to dig deeper, but you definitely need to get all the basic systems in good working order.

RustedSprinter > DogonCrook 07/14/2015 at 22:01

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Wow thanks so much for the advice.

DogonCrook > RustedSprinter 07/14/2015 at 22:08

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No worries. Sorry if it’s a bit of a ramble. I’m intrigued by your issues lol so definitely keep posting, but I’ll help anyone trying to keep older cars running, I hate to see them cast aside.

RustedSprinter > DogonCrook 07/15/2015 at 16:45

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Yeah I hear that! It was raining again today. I got the check engine light to flash. It flashed one then 2.5secs later 4 flashes. Not sure how to read that. Then i disconnected the jumper and tried to start it but it wouldnt start I heard something spark maybe cuz it was wet.

DogonCrook > RustedSprinter 07/15/2015 at 17:12

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That’s definitely your coil or wires arcing you might have a pending code now but not sure whether you have an ecu that would store them. You might be lucky here. So once the eltricity finds a way through it’ll keep happening and leave visible damage to the coil case or boots. If it’s constant you can have somebody crank it for you at night and likely see it happening. I’d pull that cover and the wires and dry everything out might as well do new spark plugs because they are cheap and make sure to use dielectric grease on every connection. Check the coil body for signs it’s arcing through the case and either test it or buy a new one if it’s really old.

You might need to get cover for your car I’m not sure how you can prevent it. Somebody may have a solution on the forums but the fix for my 914 was never get the damn thing wet lol.

DogonCrook > RustedSprinter 07/15/2015 at 17:22

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Looks like you have an ignitor as well. Look up how to test that and or hunt one down on eBay, a forum, or a junkyard.

Google a bad ignitor for your car, looks like it throws a code and it’s common it cuts power at 4k rpms. Seems like this may be your main problem.

RustedSprinter > DogonCrook 07/15/2015 at 17:26

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This may sound silly but where is the coil body? And the wires your talking about are the spark plugs wires right?

RustedSprinter > DogonCrook 07/15/2015 at 17:29

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Also that code is for a water temp sensor? That makes no sense to me.

RustedSprinter > DogonCrook 07/15/2015 at 17:49

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I’ll add that to my list to check. Thank you so much!

DogonCrook > RustedSprinter 07/15/2015 at 17:49

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Yeah the wires go from the spark plugs to the distributor, and from the center of the distributer to the coil. Be careful around a coil, it can pop you really good and turn a wrench red hot in the blink of an eye so read up on that. The coil will be slightly larger than a can of red bull. The wire going from it to the distributor looks like a spark plug wire.

DogonCrook > RustedSprinter 07/15/2015 at 18:01

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Ok this is your dying while warm problem and it might be intermittent from water getting to the wires. So if your car can’t tell what temp the coolant is it will never get the air fuel mixture right. But cars also have systems to assist in cold starts. Your car has a fuel injector that feeds extra fuel into the fuel rail and supplies all four cylinders with extra fuel during warm up. It is supposed to shut off gradually as the car warms up, but if it can’t detect the temp, it will never do that. This causes the engine to become way too rich as the car warms. It’s called a cold start injector. Test your temp sensor or replace it and you may have a break in the wires so look real carefully at those. An air bubble in your coolant could cause this as well if the bubble ends up under the sensor, so look up how to burp your coolant system, it’s usually not too much trouble.

RustedSprinter > DogonCrook 07/15/2015 at 18:09

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Wow man I cant thank you enough for your advice. I’ll check that out tomorrow!

DogonCrook > RustedSprinter 07/15/2015 at 18:19

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No worries, these two issues could both cause all the symptoms you are having so tackle them first and you can probably get it back on the road. Then you can take your time going over erything else, it’s much less stressful doing preventative maintenance than hunting problems.

RustedSprinter > DogonCrook 07/20/2015 at 19:01

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Hey just wanted to give you an update! Gave the MR2 a mini service and shes running a bit better. New sparks, wires, air filter. Like you said the old wires were a bit wet. I put some of that gas cleaner stuff Gum out I think its called in her and she ran well for about 5 mins! I think the TPS isnt opening the throttle body enough. I got a code off of it for TPS so Im going to pull that off and put a new one on. I tested the TPS with a multi meter and its messed up. My mechanic didnt set it when he took it off. The battery I got from pep boys is a dud so I need to return that. I get good volt readings when it runs but the dam battery wont hold the charge.

DogonCrook > RustedSprinter 07/21/2015 at 11:42

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Sounds like its going pretty good. I’ve had dud batteries before and I’ve had them fail after a single full discharge, so hopefully that’s what’s going on. Hunting shorts is not a fun job if they are intermittent. I’d check the wires to what you are getting codes on, and the bundles they go into for obvious stuff, sometimes manipulating the wires triggers it and you’ll get a spark or a puff of smoke. If it’s not your daily driver you may have to pull the battery and keep it on a tender when your not driving it till you find it, because completely discharging one takes off a percentage of the charge it can hold every time.

After you swap the tps, and the coolant sensor or get that reading good, I’d swap the fuel filter and pressure test the fuel system. On your car take the reading off the hose that leads to the cold start injector. I’d also look for a place around you that can test injectors or find a place you can send them. It’s the smallest opening in the system and most likely to clog up a bit. If the new fuel filter gets it running good, you may be able to put this off a bit. If the fuel sending unit is easy to pull on your car they usually have a sock or filter that’s either cheap or easy to clean and you’ll get an idea of what your fuel tank is looking like.