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Z

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Discussion Starter #1
please help me to clearify the origin of overheat.
to my knowledge, if a car were to run lean due to lack of fuel, it would definitely make the car run hot.

now, what if the cooling system isnt working 100% (bad radiator, water pump, thermostat etc...) and the car overheats from lack of cooling, would it effect A/F ratio in any way?

because right now I need to pick an area and start digging for my lean problems. I'm almost done with my whole fuel system (except injectors, havnt taken them out yet), now I'm focusing on cooling part (135,000 radiator and 75,000water pump).

thanx

Jonas
 

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You should be able to tell your coolant temp by the meter on your dash.

Have you tried swapping your BCC like we recommended before?

Have you tried doing a compression test?

-m
 
Z

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problem fixed. I dialed up fuel pressure 0.4 bar more and increased 20% more fuel up top with my HKS AFR and my A/F ratio dropped to 12.5:1 all the way to 5th. its always the simple thing....damn
Jonas
 
N

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fyi, the stock coolant gauge pretty much tells you nothing, it has three readings... cold ------- OK ------- OH SHIT, TURN OFF CAR
 
N

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Discussion Starter #6
Zerosoul said:
problem fixed. I dialed up fuel pressure 0.4 bar more and increased 20% more fuel up top with my HKS AFR and my A/F ratio dropped to 12.5:1 all the way to 5th. its always the simple thing....damn
Jonas
you still should keep checking, i've never heard of anyone adding fuel up top on a properly running bpu. I think you just bandaided the situation.
 
W

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fyi, the stock coolant gauge pretty much tells you nothing, it has three readings... cold ------- OK ------- OH SHIT, TURN OFF CAR
Actually, OBDII data logging by Supra owners have shown that the gauge always stays in "ok" because it always is. A couple years ago, testing showed +/- 10 degrees on a BPU car in a wide variety of conditions.

A/F is purely a ratio. It is not an indicator of stress on the engine at all. You can have a "rich" A/F and still detonate, and run a "lean" A/F and run great. EGT is a better indicator of potential for damage.
 
Z

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Discussion Starter #8
NOVAsupra said:


you still should keep checking, i've never heard of anyone adding fuel up top on a properly running bpu. I think you just bandaided the situation.
I agree, but at least I know the problem is lack of fuel, and since I have almost brand new everything in my fuel system except the injectors, I will replace them next. but for now, at least I wont be running lean.
 

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Could this be it...

The first few runs made 38X RWHP but the AF was very lean. We used the afc to compensate all the way up to richening 25+%!! The car would really still not run in the right range, so something had to be wrong. Turned out the FPR didn't have a vaccume source and didn't know boost was coming on! After recconecting it the car was off the charts rich! Now we had room to tune. After many more runs, and the power rising steadily the whole time...
 
Z

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Discussion Starter #10
how much fuel pressure did you dial in on your FPR? I have HKS FPR and I'm still trying to get the right FP.
 

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This isn't my post. I just remembered reading about a similar problem and thought this might help. The guy who posted this uses the user name ADROCKTT. Contact him for details.

Well this post has been a long time coming, sorry all I was very busy with the holidays but here goes.

I traveled to Orlando over the weekend to hang out with the supra owners there as well as dyno and tune my supra. I had an amaizing trip!

I got to ride in Jesus's beast as well as Adam G's suped ra. I am definately in need of a single, as if I didn't know this before! Both cars are simply amazing and incredibly powerful. Thank you both for the rides and the company. Simply amaizing and something I will not forget.

At Sybony's speed shop, I dyno'd the car with Angel Robles on hand to tune. I can't say enough good things about Angel. He was very helpful with the dyno and even though I had a few problems, boost guage broken, car running somewhat lean, ect. He really did some awesome work. Rolo, who is the man in charge of the dyno was also great, helpful and very fair on price.

The first few runs made 38X RWHP but the AF was very lean. We used the afc to compensate all the way up to richening 25+%!! The car would really still not run in the right range, so something had to be wrong. Turned out the FPR didn't have a vaccume source and didn't know boost was coming on! After recconecting it the car was off the charts rich! Now we had room to tune. After many more runs, and the power rising steadily the whole time, the clutch began to slip.

On a slipping clutch at 15PSI at a very safe 11.2:1 AF we made 420RWHP on pump gas. With the addition of some 103 unleaded, Thanks Jesus, and boost set at about 19PSI we made a few more runs. The results were incredible. 440RWHP and 496 lbs of torque on a slipping clutch!!! I really can't wait to change the clutch and redyno again to see the real numbers. This is all out of a BPU++ car with most mods minus the VPC. (AFC, MBC, DP, exaust, cam gears, FMIC, ect.)

I went with the RPS stage 3 sprung hub clutch but with the stock flywheel. I was able to pick this up in person from Titan motorsports right there in Orlando. It was very nice to see the shop and thanks for the help in getting the clutch.

Another Dyno was my friend Mike N. who put down 175.X FWHP out of his type R with just an AEM intake and Vtech AFC+Angel's super tuning. That is an excellent dyno for that car and he has more plans to come with it soon.

Thanks so very much to all that helped, offered rides, advice and good company, and to all the Orlando crew. I'll be back soon I want to say a personal thanks to Angel, Jesus, Adam G, Patrick, Nero, Bottle, Rolo, my friends Taj and Mike who came along, Pete for a place to stay, and everyone else involved.

In other news, I am just working now on finishing up the stereo in my car which will be shown at a later date. Now that the car is all tuned, I can't even keep any traction. I hope this didn't push back my single plans with the dyno and clutch expenses but the car is AWESOME now. I love my supra more everyday.

Adam
 
C

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Discussion Starter #12
I have had similar problems.

I've got a wideband o2 on the car now and have had a widely varying range of o2 readings.

The first thing that I noticed was that when I was on long trips (30 mins+) the car was going lean. The only thing that I could come up with was that 18v to the fuel pump was causing the fuel to heat up after a while. So I removed the B and M power plus and decreased the voltage to the stock setup.

That didn't work entirely. I could drive for a little longer, but the AF's would still get lean after a while. Just then my water pump started leaking like mad and have since replaced that. The car seems to be running a bit better, however, the AF"s are still variable. I have a Fuel Pressure gauge and it doesn't appear that the fuel pressure is the problem. At the end of the curve I have it richened +12%. That seems a bit much (100 percent duty on the injectors?).

Does anyone know why my AF"s could be so variable? I am running VPC, S-AFR, and SP60.

It also doesn't appear that my EGT's are corresponding to AF.


Any ideas?

Thanks!
 
Z

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Discussion Starter #13
if no vacuum source goes into FPr the car would get only 3.0 bar of fuel no matter what...or less! how the hell did that guys supra make 38X RWHP with that little fuel?
I just did the Fuel damper bypass, hoping it will help my fuel flow a little better, I noticed my FR dropped about 0.2bar.
 
Z

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Discussion Starter #14
carcnoid said:
I have had similar problems.

I've got a wideband o2 on the car now and have had a widely varying range of o2 readings.

The first thing that I noticed was that when I was on long trips (30 mins+) the car was going lean. The only thing that I could come up with was that 18v to the fuel pump was causing the fuel to heat up after a while. So I removed the B and M power plus and decreased the voltage to the stock setup.

That didn't work entirely. I could drive for a little longer, but the AF's would still get lean after a while. Just then my water pump started leaking like mad and have since replaced that. The car seems to be running a bit better, however, the AF"s are still variable. I have a Fuel Pressure gauge and it doesn't appear that the fuel pressure is the problem. At the end of the curve I have it richened +12%. That seems a bit much (100 percent duty on the injectors?).

Does anyone know why my AF"s could be so variable? I am running VPC, S-AFR, and SP60.

It also doesn't appear that my EGT's are corresponding to AF.


Any ideas?

Thanks!
what kind of A/F reading are you getting it from? my car tend to run lean also after a long highway trip then doing a high end pull. how does your EGT reads? both my EGT and A/F correspoond to eachother pretty well, when my A/F shows lean, my EGT is high and vise versa. my A/F sensor probe needs to be heated up to about 600-800C in order to give correct reading, its a Tomei.

BTW, what fuel pressure DO you get?
 

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I don't own a mkiv-but this is kinda of general-If you have a manual-check the coolant temp sensor-not the gauge sending unit sensor. When a car is cold-the ecu reads this sensor to richen the mixture-I have seen these go bad before-maybe it is possible that the sensor could being telling the ecu the car is warmer than it really is and not providing the right amount of fuel-just a shot in the dark though........
 
C

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Discussion Starter #16
ZS,

My A/F's have gone to 14.1 to 15+ after a long drive. These were numbers resulting from 4th gear pulls near redline. My EGT's used to be real hot (900c) always, but now rarely get that hot. I have had A/F of 14+ with EGT's less than 800 before. As far as I know, 900 is the upper limit on the EGT's.

It seems to me that your problems are very similar to mine ZS...

TP,

Yeah, that sounds like a viable problem, however, my temp gauge on my dash stays put all while this is happening. I think I will be getting a fluidyne soon to overcome some other problems that I have had recently.

Any other thoughts?

Thanks!
 

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carcnoid said:
ZS,

My A/F's have gone to 14.1 to 15+ after a long drive. These were numbers resulting from 4th gear pulls near redline. My EGT's used to be real hot (900c) always, but now rarely get that hot. I have had A/F of 14+ with EGT's less than 800 before. As far as I know, 900 is the upper limit on the EGT's.

It seems to me that your problems are very similar to mine ZS...

TP,

Yeah, that sounds like a viable problem, however, my temp gauge on my dash stays put all while this is happening. I think I will be getting a fluidyne soon to overcome some other problems that I have had recently.

Any other thoughts?


On all other toyotas I can think of-there are two different sensors-one just for the gauge and one for the coolant temp signal to the ecu-if say the coolant temp to ecu signal sensor was shot-but the sending unit to the temp gauge was alright-your gauge would remain normal-just a thought
Thanks!
 
Z

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Discussion Starter #18
carcnoid said:
ZS,

My A/F's have gone to 14.1 to 15+ after a long drive. These were numbers resulting from 4th gear pulls near redline. My EGT's used to be real hot (900c) always, but now rarely get that hot. I have had A/F of 14+ with EGT's less than 800 before. As far as I know, 900 is the upper limit on the EGT's.

It seems to me that your problems are very similar to mine ZS...

Thanks!
wow.....14+ A/F is NOOOOOO good.....are you using a wideband O2 sensor? where is your EGT probe mounted at? I assume its before the turbo in the manifold? if its on DP, 900C is gonna melt your rings. my A/F is bad, but not as bad now, its down to 12.5 at the end of 4th gear pull, EGT has dropped also after I dialed in more fuel pressure. you might have a fuel issue....
 
C

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Discussion Starter #19
ZS,

The EGT sensor is mounted before the turbo. It is a wideband O2 and yes, 14+ is insane.

One of the problems that I had experienced was because the S-AFR was set in the self learning mode. This was causing the car to go extremely rich when I let off the gas (to prevent stalling). I have since taken it out of this mode and solved some of my problems. But even still it seems very irratic.

Doing top end pulls my EGT's will be sitting at 12.1 or so and EGT's will be hitting near 900c.

You have the S-AFR too right?

Anyone else have any thoughts?

Thanks!
 
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