I recently bought my first Toyota, an 89 MR2, and I've discovered my first drivability problem. When I start the car cold it works great, no complaints, but if I drive the car somewhere, turn it off and let it sit for maybe, 5-30min then start it again it idles around 500rpm and sort of bounces around. It dies sometimes and I have to keep giving it gas even at a stop to keep it running. If I let it idle long enough the Check Engine lamp comes on, but if I turn the car off then on again it goes away. I'm thinking it's a sensor such as the MAF or IAT (I'm not sure what sensors this MR2 has exactly, I haven't bought a repair manual yet). Anyone else had this issue and solved it successfully?
First try the easy way out.... Bleed your coolant. I know it sounds crazy but MR2's cooling systems are very touchy and if there is an air pocket (generally happens close to the water temp sensor) it can cause a cool spot on the sensor and then when you rev it creates a hot spot....this basically confuses the ECU into thinking the engine is cold.....then its hot, and in turn causes the Cold start injector to fire wildly and also mess with the other sensors. go to www.mr2oc.com and search on the main forum page for "bleed coolant" and you will find out the proper way to do it. ITs a bit more complex with a MR2 then a normal Front engine car.
If that doesnt help, you may have a bad vacuum line, as the rubber gets old it gets tiny cracks in it, which can get bigger when the hoses are cold. When they are hot the hoses expand a bit and the cracks shrink. get a can of ether and spray on your vacuum lines one at a time as the car runs...if the idle goes up you found the leak. Be carefull not to spray near the exhaust manifold.
Ok, thank you very much I had no idea the coolant could get air pockets and cause sensor issues. I haven't had a chance to poke my head around in the engine bay yet but I plan to clean it this coming weekend so hopefully when I clean all the dirt and grime out I can find out if any of the lines have cracks and start replacing them (I'd planned on doing this anyway when I replaced the fuel system to be sure I get the max mpg I can since this will be my daily driver for a few years probably).
if the coolant and the vacuum line thing doesn't work, you can also look to the TPS.
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1/2 a tank of V-Power gas+ 1/2 tankful of fuel with Techroline= V-Tec gas??? Speed and grip walk a very thin line of balance. If a car feels like it's on rails, then you're probably not going fast enough.
Last edited by ToyotaTechGeek; 01-17-2010 at 07:39 AM.
Reason: removed link
Thanks for the link, it's for an 88 MR2 but I'm guessing the 89 and 88 are the same car since the other manuals out there are 85-87. This will definatly help me get started identifying everything in the engine bay. I appreciate the help guys.
Elliot,
Did you copy the link or complete the download yet?
I will have to remove the link as it's not only against forum rules, but also against the law in regards to copyright infringement.
Sorry guys!
PS. I have no control over this kind of thing being done via PM..(hint)
So I've done a little bit of cleaning and looking around, the hoses all look good for now but I'll replace them as money allows (still looking for a job unfortunatly it could be a while before money for repairs comes in). I might try experimenting with a different tempurature thermostat and maybe different psi rated radiator caps to see if I can't get the car to run a little cooler. It's cold outside right now, but I'm starting to worry the car might over heat come summer time considering I have to climb a pretty nasty hill to get to school every day.
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1/2 a tank of V-Power gas+ 1/2 tankful of fuel with Techroline= V-Tec gas??? Speed and grip walk a very thin line of balance. If a car feels like it's on rails, then you're probably not going fast enough.
It could be as simple as a plugged vacuum port for the FPU system (Fuel Pressure-up System). It helps raise fuel pressure during cold start, hot restart, hot idle, and wot. If the vauum port for it becomes plugged your fuel pressure will be abnormally low during these conditions.
I recently had this issue, and after cleaning the vacuum port, the car once again idled perfectly, and accelerated a bit better.
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So long and thanks for all the fish!
It's OK Tony. I'm glad you could help Elliot with that. Toyota came down on Toyota Nation about having free links of their manuals. They said it was copyright infringement and if we posted them, they would sue us.
I suggest just PM'ing the link. That keeps TN in the clear.
You are very much appreciated here
It could be as simple as a plugged vacuum port for the FPU system (Fuel Pressure-up System). It helps raise fuel pressure during cold start, hot restart, hot idle, and wot. If the vauum port for it becomes plugged your fuel pressure will be abnormally low during these conditions.
I recently had this issue, and after cleaning the vacuum port, the car once again idled perfectly, and accelerated a bit better.
Interesting you bring up the acceleration point because I took the car out onto an unused road near my house to try and learn where the grip break point was for the rear end of the car incase I ever lost control in the rain, etc I could control it better. The car does seem to have limited acceleration considering the power it has. My Honda Del Sol had 125bhp and weighed ~2350 but the MR2 weighs a little less I think (like ~2150?) and has 5 more bhp (I think the 89 was up'ed to 130bhp N/A) yet it feels a so much slower in a straight line then my Honda did. I guess I should really just clean everything in there and see what happens, sounds like this could be a number of small issues adding up into one notice-able issue.
The 4age was an exceptionally well planned engine, and everything on it has its purpose. That is why extreme aftermarket measures are generally required to enhance the performace of one in good repair. For example, while one might usually find that disabling smog systems, on the average car, might well help enhance its performance, you won't find that on the MKI. Everything was very well accounted for and incorporated to its fullest. If you ever do find that modifying any of the oem systems seems to increase performance substantially, you will most likely find that something else is not working properly, and your recent change has done nothing more than compenstae for the actual problem somewhat.
I've owned on of these since they first came out, have tried virtually every trick there is, and researched it to no end. Bottom line is that it is a great motor, but after 20 years, or so, a lot of little things can get gummed up, etc. Even rebuilt engines often have little overlooked items that can hinder its potential. Just cleaning all vacuum ports can often bring surprising results. Heck, I've even gone through and cleaned every electrical connector in the engine compartment. The difference wasn't necessarily breathtaking, but was noticable just the same. Every little thing adds up!
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So long and thanks for all the fish!
The 4age was an exceptionally well planned engine, and everything on it has its purpose. That is why extreme aftermarket measures are generally required to enhance the performace of one in good repair. For example, while one might usually find that disabling smog systems, on the average car, might well help enhance its performance, you won't find that on the MKI. Everything was very well accounted for and incorporated to its fullest. If you ever do find that modifying any of the oem systems seems to increase performance substantially, you will most likely find that something else is not working properly, and your recent change has done nothing more than compenstae for the actual problem somewhat.
I've owned on of these since they first came out, have tried virtually every trick there is, and researched it to no end. Bottom line is that it is a great motor, but after 20 years, or so, a lot of little things can get gummed up, etc. Even rebuilt engines often have little overlooked items that can hinder its potential. Just cleaning all vacuum ports can often bring surprising results. Heck, I've even gone through and cleaned every electrical connector in the engine compartment. The difference wasn't necessarily breathtaking, but was noticable just the same. Every little thing adds up!
Yeah I'm trying to keep my engine stock but I guess a good solid cleaning of everything I can get to without pulling the engine is a good start.
Heck, I've even gone through and cleaned every electrical connector in the engine compartment.
and lubed every connector with a seal!
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1/2 a tank of V-Power gas+ 1/2 tankful of fuel with Techroline= V-Tec gas??? Speed and grip walk a very thin line of balance. If a car feels like it's on rails, then you're probably not going fast enough.
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