Need Help, horrible bogging.. Long description & Video - Toyota Nation Forum : Toyota Car and Truck Forums

deputy865 · 07-10-2011, 01:28 AM

1991 Turbo MR2 (3SGTE, Swapped, 95% stock)

The Story:

Just picked this car up a week ago. Previous owner was supposed to meet me at our predetermined meeting spot. I planned on trailering the car home and had already driven the 2 hours to get to the meeting spot. I get a phone call from the previous owner, the car is bogging really bad and is acting up and he is working on trying to figure it out(Go figure, was perfectly fine until now). He had JUST filled it all the way up with gas and was on his way when it started doing this, suddenly. I find this hard to believe because the car is undrivable in its current condition. He changed the spark plugs and oil. Gave me money for a new fuel filter, spark plug wires and an o2 sensor, thinking 1 or all of these things could be an issue.(Also got 4 brand new tires in the deal) I took the car since I was already down there and went on my way. Nice MR2, needs a better paint job, but rust free and very clean.

The Problem:

Car idle's like COMPLETE s*** and will not go above 800rpm~ even at WOT.

Here is a video I took of what the car is doing. Take note of the boost gauge and vacuum as well as RPM's. The video makes the knocking sound a lot louder then it really is.

You Tube

Moving forward.

The CEL was on, so I did the paperclip trick and got the codes from the car. Here is what I got:

22 - Throttle Position Sensor (Did OHM check, tests fine)
24 - Vehicle Speed Sensor (Speedometer doesn't work)
31 - Gear Position Switch (Shift linkage is messed up)
34 - MAP Sensor Curcuit Error (???)
35- IAC Problem or Idle Error (No S*** lol, ???)

I can already rule out codes 22, 24 and 31. 34 and 35 are my big concerns right now. I'm trying to check to see if my IAC is dirty or faulty, but I'm having issues getting the damn thing off so that will have to wait.

When I went to pull the codes, I had a hard time finding the diagnostics port for the car because it was not where it was supposed to be. Instead I found it free-hanging between the intake manifold and the trunk wall. Also, there was a plug unplugged which I later found out was the MAP sensor plug.. I still cannot find out where it plugs into and I've looked just about everywhere it should be. Now I know the car is swapped, but I'm not sure what gen wiring harness was used or any of that. So I wonder if the MAP has always been unplugged, or if the plug fell out leaving the sensor on the road somewhere(someone not bolting it up or plugging it in tight)?? This is my most main concern right now. Where the MAP goes and IF I need it or not, I'm assuming I do. Should I buy a new map sensor and plug it all back up?

I'm clueless right now as to what is wrong with the car. Could it be something totally different or is the unplugged MAP sensor wreaking havoc on everything? Or could it be something way off the beaten path messing everything up? Here are a few things that have been suggested to me or possibilities I thought up:

Timing? (Some say yes, some say no)
Bad gas?
Wrong gas; 87 instead of 93 on accident (Previous Owner accident?)
Stuck Injector?
Bad Fuel Filter?
Spark Plug Wires?
o2 Sensor?
Tiny Unicorns poking holes in hoses and sh**ing in filters? (Dane Cook lol)

I'm always online and can provide any more information if need be, quickly.. I've got my concern posted on a few forums right now and have gotten several answers, but things have slowed up and or been ruled out.. I want this fixed ASAP!

Any and all suggestions would be greatly appreciated.

jrovnak · 07-10-2011, 08:06 AM

I'm not sure if this is the same problem....but I had experienced the exact same symptoms. Any acceleration above 1K rpm would bog down like it had a defective carbonator, not fuel injection. After a half day or so of looking I discovered I had a leak in the Mass Airflow Meter. I opened up the top (Removed the plastic/rubber) lid. I noticed the Mass Airflow Meter vacuum was sucking in water and the moisture was collecting in the mechanical/electronics of the Mass Airflow Meter. I used a shop vac to remove the water,(this alone did not correct the problem) and after that some electronic contact cleaner and some throttle body cleaner. Slapped the lid back on and all went well until the next rain storm.... I had to do the Vacuum, electronic contact cleaner, and some throttle body cleaner again. However, this time I added the rerquired black silicone sealant around the lip or rim of the plastic/rubber lid and sealed the lid to the Mass Airflow Meter. This fixed my Bog problem for good. Might be worth a try....especially if the seller happened to have shampooed the engine right before meeting you. Good luck!

deputy865 · 07-10-2011, 07:37 PM

I'm gonna try to clean the MAF with some contact cleaner.. I can't seem to pull the sensor out of my MAF (its a lot different then yours I'm assuming). I'll spray it down, let it dry and see if that helps any.

Going to go with simple stuff tomorrow though. New plug wires and a fuel filter.

jrovnak · 07-10-2011, 09:02 PM

Good luck.

andyb16 · 07-13-2011, 02:57 AM

87 octane won't cause it to not run right, it will just knock a lot easier. It should still idle fine, so I'd rule that out. Now, whether or not there was water in the gas is a different issue. I kinda doubt that's it either. My guess would be a bad MAP, bad AFM, or a boost/vacuum leak.

Double and triple check all your vacuum hoses, then check them again. Gen 2s hate vacuum leaks.

deputy865 · 07-13-2011, 07:11 AM

Quote:

Originally Posted by andyb16

87 octane won't cause it to not run right, it will just knock a lot easier. It should still idle fine, so I'd rule that out. Now, whether or not there was water in the gas is a different issue. I kinda doubt that's it either. My guess would be a bad MAP, bad AFM, or a boost/vacuum leak.

Double and triple check all your vacuum hoses, then check them again. Gen 2s hate vacuum leaks.

Should all the vacuum lines be hooked up or can I cap some off? I come from the DSM world and we always capped our lines off lol.. Is it the same case with the MR2's?

Shane

***MR2Jedi*** · 07-13-2011, 07:51 AM

Quote:

Originally Posted by deputy865

Should all the vacuum lines be hooked up or can I cap some off? I come from the DSM world and we always capped our lines off lol.. Is it the same case with the MR2's?

Shane

Depends on which lines.

deputy865 · 07-13-2011, 07:59 AM

Quote:

Originally Posted by MR2Jedi

Depends on which lines.

Well thats what I'm trying to figure out.. Which I can cap, which need to be capped and which need to be kept going.

From memory, the two on top of the throttle body have 1 really short vacuum line connecting both of the two. So thats eliminated. There are two open ports on my IAC, not capped, not hooked up to anything, just open.

Those are the only ones I can remember without looking at the car. Are there any others that NEED to be hooked up? I live in Michigan, so we don't have strict emissions around here.. I'd like to just eliminate all the ones that I don't HAVE to have hooked up. Save myself vacuum and boost leak issues down the road

There is a boost gauge installed.

Shane

***MR2Jedi*** · 07-14-2011, 01:09 AM

Sounds horrible in your video. I think you do have some vacuum issues/leaks.
You can use your computers zoom to view this vacuum diagram.

deputy865 · 07-14-2011, 07:12 AM

Quote:

Originally Posted by MR2Jedi

Sounds horrible in your video. I think you do have some vacuum issues/leaks.
You can use your computers zoom to view this vacuum diagram.

Thank you.

Now which an I cap off and which must be left untouched?

***MR2Jedi*** · 07-14-2011, 09:03 AM

Off the top off my bald head, the only vacuum lines I can think of that you can block off/eliminate are the boost sensor, which will ilimiinate boost cut and the stock boost gauge. And the EGR lines if you remove the EGR.
The rest need to be connected .

The small one you said you capped off is for the EVAP Charcoal canister.

deputy865 · 07-14-2011, 09:50 AM

I'm not anywhere near my car, but I've been under the hood enough times lately to remember what I don't have or that is capped off:

- I don't have my MAP, so that is gone.
- "E" and "P" are routed to eachother, so those are eliminated.
- I don't have a charcoal canister, so anything connected or related to that is gone.

The rest is a mystery.

I have a good 1992 3SGTE Diagram, I'm assuming that 1991 and 1992 are the same as far as vacuum goes?

Shane

deputy865 · 07-14-2011, 07:51 PM

Update:

Checked all the vacuum lines.. Everything seems to be either capped off or hooked up... Don't think I can rule these entirely out though just yet..

I need to reset my ECU.. Try to get some fresh CEL codes.

I sprayed contact cleaner into my TPS and MAF ports as well as changed the plug wires with NGK wires. Didn't get any different result.. Was a bit discouraging, but I know I still have my distributor cap and rotor coming in on Saturday. Still have to install my new fuel filter as well.

Anything else to check or do while I'm waiting for my parts to come?

Shane

EDIT:

Forgot to mention, when I got the car and first started looking around, I noticed this wire was unplugged. Its hard for me to tell you exactly where it plugs in.. But its almost RIGHT under the distributor. It also screws in vertically. It tightens around a little rod. Not sure what it is. It is protected by a foam tube where it might come into contact with anything hot and works its way around the engine and goes under the car. Its a black wire, about as thick as the average vacuum hose. I screwed it back in as tight as I could, no change in the vehicle. Not sure what the hell it is...

billups · 07-14-2011, 08:47 PM

Fuel cut... And you are experiencing that because you have no MAP? Not sure yet.. Can you get a picture of where the MAP should be and the diagnostic port? None of those codes would cause the car to run like that.

Lastly, check that the knock sensor is plugged in. It is located underneath the intake manifold by the main engine ground...

deputy865 · 07-14-2011, 08:57 PM

Quote:

Originally Posted by billups

Fuel cut... And you are experiencing that because you have no MAP? Not sure yet.. Can you get a picture of where the MAP should be and the diagnostic port? None of those codes would cause the car to run like that.

Lastly, check that the knock sensor is plugged in. It is located underneath the intake manifold by the main engine ground...

Any help or pictures of what the knock sensor looks like? The MAP and Diagnostics port are supposed to be bolted to the trunk wall, behind the throttle body.. But mine was just hanging there. I think the MAP sensor was either deleted or fell out.. I heard some people take it off to prevent fuel cut at higher boost levels, but I was told this car has been left at stock boost level. I've got to believe it because there isn't any form of boost controller on the car. Does have a boost gauged though, but that is normal.

You think my ECU is fuel cutting itself for no reason?

Shane