MR2 Hesitation and Low Oil Problem

[BokCh0y]

I just picked up a 91 MR2 Turbo with only 89000 km's (about 55000 Miles). Car is in immaculate condition but it's hesitating at low RPM's between 1500-2500 rpm's but only when the car is cold. While driving COLD the car hesitates and jerks forward and backwards. Give it gas and nothing until the boost kicks in and it passes 3000 rpm. Can even hear what sounds like a backfire at low rpm's when the windows are down - usually at about 2200 rpm. After driving it for about 5 minutes once the car fully warms up, it runs smooth and pulls strong. I've changed the parts listed below:

Plugs
Plug Wires
Dist. Cap
Rotor

All these parts were changed about 2 weeks ago with Genuine Toyota Parts. After they were changed the car seemed to run better and smoother and the hesitation was gone but has since then returned. Anyone have any ideas on why or what to check for next? The old plugs and wires from the previous owner were not OEM and once the plugs were removed and upon inspection, they were black in color at the ends - carbon build up. Also my exhaust tips seem to have a lot of carbon build up on them.

Also have another weird problem. I had the dealership perform an oil change on it a couple days after I purchased it. Using Mobil 1 Synthetic 5w30 oil. Anyways yesterday while I was driving home the low oil light flashed. I immediately pulled over and checked the oil. Was down a Litre??? So I hit the nearest petrol station and bought a Litre of Mobil 1 5w30. Tossed it in checked the dipstick again and it was brought back to full. My question is why would I be down a Litre after less than 2000km (1200 Miles) of driving? The car does not blow any smoke at all and I can't see any leaks or signs of drips on my driveway or underneath the car.

Also getting some terrible gas mileage and sometimes has trouble starting. Will turn over and crank but does not always catch right away. Need to pump it occasionally.

Does anyone have any suggestions about these issues? Do I have a boost leak or vac leak and if so how can i check and remedy this problem.

Could the hesitation be caused by a defective O2 sensor or MAF sensor?

Am I burning too lean/rich and if so how can I tell and how do I remedy this?

Could it be a defective ignition coil?

Thanks in advance for the help everyone.

[2.2vtec]

mr2 are known for a defective ignition coil, had the same problem in my 91 turbo.

[jvillain]

What do you know about the car before you bought it. What if any mods were done to it? Can you have a look at the injectors and tell us what color the top of them is. Not the color of the connector that plugs into them. Do you know if there were any piggybacks installed. Does it have a stock ECU? Is it a North American engine or a JDM engine.

MR2s really like to leak oil. I would get underneith it and start feeling around every where down there and see if you can see signs of oil. The likely culprits are the valve cover and the oil pan. You can get 3S-GTE oil pan gaskets from Autovalue and they are worth their weight in gold.

[BokCh0y]

From what I understand from the previous owner is that the car has been babied since day 1. Original had the car dealer maintained with all service records. Ended up buying an acrage near crossfield and had the car in storage for the last 4 years.

As far as upgrades and such, the car is a local Calgary Car, not JDM. Everything is stock with the exception of the 93+ MR2 rims in mounted and the k and n filter. ECU is standard USDM/CDM issue.

I'll check the injectors and see if i can take a better look underneath the car to see if there are any leaks i'm missing.

[jvillain]

In that case I would lean towards a vacume leak of some sort. It has been a long time since I have had all the factory air hoses but the one I remember leaking that came closest to doing what you describe is the one running from the valve cover to the throttle body. I would take it off and try bending it. Because of the curves in it it can get a crack and only open enough to be able to see under preasure.

The thing with vacume leaks is that a small leak is more noticable at low rpms because there isn't much air moving through the engine. As the RPMS climb a small leak can get lost in the huge volume of air moving through the system.

Any ways check all of the hoses. I know there are lots but you should start to get familliar with them.

[CelicaST-162]

Check the AFM->turbo inlet hose....those tend to crack a lot as they age. When it's cracked, it will let unmetered air in, and cause the jerking, stalling issue.