Running Lean

Ok... Different VR4 same problem... but this time it aint gas... I dont think.
My freind has a 93 VR4 he has a few basic bolt on mods, he has Greddy 13gs turbos, a walbro feul pump complete full system with aeromotive FPR and he runs stock injectors. he has i think a few more upgrades but they dont really mater...

Ok his was sorta doing the same thing as mine... so we did the same thing as i did... so we drained the gas and went and get some new gas that we knew was good, changed fuel filter and spark plugs... and try to run it like we did mine, except the results where much different... Mine ran perfect, his... on the other hand got even worse... we check the injectors no leaks... and tried unpluging the o2 sensors to see if there was any change... none, check engine light comes on but only when car is started so we cant read the code... any ideas? he said it switched over really quick... from running perfect to shit.

so if you have any ideas let me know, because now i have a car in my shop thats in my way. and now i cant work on anything else until his is moved :(

Even if the CEL comes on only when its started the code should still be stored in the ECU. Go pull it.

^i'm pretty sure that the CEL illuminates upon start-up on every car. this is normal. its supposed to stay lit for about 10 seconds, then goes away. if it remains lit, then it means the ECU is throwing a code.

i could be wrong. though it wouldn't hurt to check for a code.
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could you explain HOW his car is running?

it sounds as if you went through the whole fuel system and that checks out ok. next thing i would do is check electrical, make sure its all hooked up (MAF and other sensors around the intake adn block). then i would check the timing.

recently my friend's 92 started running very poorly, he reported 12 mpg and a huge loss of power. at WOT power would come on very slowly and much less than it should be. we suspected timing, having just reset the timing re-using his tensioner. his timing had come off again! so we replaced the tensioner, voila, runs great now.

i'm not saying its always timing, but even though you think its fuel related, the timing could have gone too at that same time, just coincidentily.

what boost is he running?
what fuel presure is he seeing at idle? how about under load?
when is it going lean?
how do you know its going lean?

^i'm pretty sure that the CEL illuminates upon start-up on every car. this is normal. its supposed to stay lit for about 10 seconds, then goes away. if it remains lit, then it means the ECU is throwing a code.

i could be wrong. though it wouldn't hurt to check for a code.
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could you explain HOW his car is running?

it sounds as if you went through the whole fuel system and that checks out ok. next thing i would do is check electrical, make sure its all hooked up (MAF and other sensors around the intake adn block). then i would check the timing.

recently my friend's 92 started running very poorly, he reported 12 mpg and a huge loss of power. at WOT power would come on very slowly and much less than it should be. we suspected timing, having just reset the timing re-using his tensioner. his timing had come off again! so we replaced the tensioner, voila, runs great now.

i'm not saying its always timing, but even though you think its fuel related, the timing could have gone too at that same time, just coincidentily.


I thought he meant it stayed on while running. But yes it does come on momentarily and then goes off when first starting.

What boost is he running, and what air/fuel control does he have. My guess is he's overrunning the stock injectors.

no no no, he has had these turbos for a while, stock injectors are not a problem. its running lean even at idle, its almost a 40 when at idle, so when dont even try to drive it due to its condition, so no load. when i check fuel pressure it was at 325 KpA (40 - 45 lbs) fuel pressure perfect.
Ive check for fuel leaks, none. so the code is stored even if the light is not on? because it only comes on when it relizes the car is lean. I know what its going to say "Sytem too lean" because it doesnt come on until the car has been running for a min. plus i have tried to read the damn code with the
f-en voltameter AND I CANT DO IT!!!! I DONT EVER GET IT RIGHT, ITS THE MOST STUPID THING MITSU HAS INVETED, PULLING CODES WITH VOLTAMETER! oh well i geuss yall dont have any ideas?...

so no the boost is not too much... the injectors are suffecient, the fuel pressure it perfect! it has to be a sensor, that or something wrong with the feul, any ideas, ANY?

^ Yeah, if the code is on for a brief period it should still be stored in the ECU. You could get a voltmeter to pull it. Otherwise try a dealership...but they will charge you an outrageous amount.

get a DATALOGGER to pull the code. its EASY, CHEAP, and COMMON SENSE to datalog when you're FI. i don't know why more people don't have a datalogger. it just makes sense to me to want to watch knock count and other parameters.

get a DATALOGGER to pull the code. its EASY, CHEAP, and COMMON SENSE to datalog when you're FI. i don't know why more people don't have a datalogger. it just makes sense to me to want to watch knock count and other parameters.


Seriously, if I had a first gen and could log knock, this would be the first thing I would have bought for my car.

Yes the code is still stored...even if you turn the car off. Get a datalogger and pull it. You 2 could split hte price and then both use it when necessary.

Red, please humor me, what boost is he running? What air/fuel control? And how do you know it's going lean at idle?

He is running 18 psi to red line, when running normal. he has the Inovate wideband LM1 Kit. I know its lean at idle because im watching the gauge...
It gets even more lean when it is under a load. and the guage is not wrong, i can feel the car and how rough it is. and i can smell the exhuast and smell that lean smell.

The gauges is at 40 what? 40:1 A/F? The car wont stay running at 40:1 I will garantee you of that.

Mitsu didnt invent pulling codes with a volmeter. All the old systems work that way, and its more of a work around to buying something to pull the code, than the way it was intended to work. So dont be mad at mitsu because you are too cheep to do it the right way.

If you have good fuel presure at idle and are running lean you are very likely looking at a fuel injector problem. Unplug the harnesses from the injectors and check the resistance across them. I think they should be around 3 ohms.

Other things to check are the MAS and the o2 sensors.

He is running 18 psi to red line, when running normal. he has the Inovate wideband LM1 Kit. I know its lean at idle because im watching the gauge...
It gets even more lean when it is under a load. and the guage is not wrong, i can feel the car and how rough it is. and i can smell the exhuast and smell that lean smell.

I really hope he running race gas all the time. 18psi on 13g's with stock injectors........amazing

I really hope he running race gas all the time. 18psi on 13g's with stock injectors........amazing


Exactly what I was thinking. There is no way 360cc injectors can flow enough for that on pump.

First off he has had these turbos for over 4 months... according to greddy, they are bolt on. I know this becasue i ran them on my car for a month but i decided i would go a bit bigger. and the possibilty of all 6 injectors going out all at once is unlikley, and most OBD1 cars used beep codes or the check engine light it self flased so many times to tell you the code.
and yes it varies from 30:1 to 40:1 AFR.
and i did end up pulling the code... all it said was System Too Lean
I know a guy who has the snap on tool (the one that cost $25,000) and we check the codes and thats all it gives me... and i already knew the system was too lean...
So please forget the idea of the injectors or turbos being the problem... there is either something electronic wrong (O2 sensors, ecu, MAF, ect...) and to my knowledge the ECU makes the system rich when relizeing that one of these are bad except of course the ECU going out itself... and the ECU seams perfectly fine to me.
and also by the way back on the injectors, they are brand new from mitsu, because his 3000gt we found in a junk yard with out egnine or tranny and i had a spare long block from my old mitsu laying around and we peiced it together and alot of stuff had to be ordered new like the injectors... by we did go with alot of after market, this car has been running great for alomst a year. I know these cars in and out, ive had a few of them complete torn down. this is why this doesnt make any sience.
and yes all these things you have said has crossed my mind and i have gone down a very long check list and i still havent had any luck finding out whats wrong.

no offense, you may feel you know these cars in and out, but the bottom line, there is no way you can safely run 18psi on stock injectors, just absolutely no way.

First off he has had these turbos for over 4 months... according to greddy, they are bolt on. I know this becasue i ran them on my car for a month but i decided i would go a bit bigger.

Just because it bolts on to the car doesnt mean you can run them as hard as you want without other upgrades. My TD05 14b's bolted right on to my car. Did I run them with stock injectors, fuck no. "bolt on" is one of the most missunderstood terms in cars. 99% of parts bolt on.


and the possibilty of all 6 injectors going out all at once is unlikley, and most OBD1 cars used beep codes or the check engine light it self flased so many times to tell you the code.


Did I say all 6 injectors went out? No
I was saying you should test all 6 because 1 may have failed. And the only way you will find out which injector is bad is to test them all. New parts fail too. If 1 injector isnt firing, you will end up with a ton of oxygen not being burnt and the car will run and get stupid crazy lean numbers due to all the extra oxygen in the exhaust.


and yes it varies from 30:1 to 40:1 AFR.
and i did end up pulling the code... all it said was System Too Lean
I know a guy who has the snap on tool (the one that cost $25,000) and we check the codes and thats all it gives me... and i already knew the system was too lean...


A car will not run at a 30:1 -40:1 afr if all the cylinders are working correctly, it will barely run at 18:1 - 20:1, hell it probably wont.


So please forget the idea of the injectors or turbos being the problem... there is either something electronic wrong (O2 sensors, ecu, MAF, ect...) and to my knowledge the ECU makes the system rich when relizeing that one of these are bad except of course the ECU going out itself... and the ECU seams perfectly fine to me.


Check your ego and your pride at the door. You ask for help then refuse to try something that takes maybe 20-30 minutes that is dirrectly related to the fuel system. I wont forget the possibilty of it being a bad injector until you test them and tell me Im wrong. If you do that then I will be perfectly will to admit I was wrong. I have no problem with that.

You are right that the ECU should be adding fuel if it thinks its running to lean. What would stop the ECU from adding fuel? Maybe an injector isnt firing or is clogged?


and also by the way back on the injectors, they are brand new from mitsu, because his 3000gt we found in a junk yard with out egnine or tranny and i had a spare long block from my old mitsu laying around and we peiced it together and alot of stuff had to be ordered new like the injectors... by we did go with alot of after market, this car has been running great for alomst a year. I know these cars in and out, ive had a few of them complete torn down. this is why this doesnt make any sience.
and yes all these things you have said has crossed my mind and i have gone down a very long check list and i still havent had any luck finding out whats wrong.

I know ive never heard of a brand new part going bad before........

As far as you knowing these car in and out. I dont think so, if that was the case you wouldnt be posting here asking questions, you would be posting here letting people know that if this happens this is how you fix it. You have yet to show any real knowledge on these cars at all, you refuse to listen to people who do, and you give all sorts of wrong info out.

You are right that the ECU should be adding fuel if it thinks its running to lean. What would stop the ECU from adding fuel? Maybe an injector isnt firing or is clogged?

have you checked the ECU for leaking capacitors, yet? that's a possibility.

[quote=talskinyguy]Just because it bolts on to the car doesnt mean you can run them as hard as you want without other upgrades. My TD05 14b's bolted right on to my car. Did I run them with stock injectors, fuck no. "bolt on" is one of the most missunderstood terms in cars. 99% of parts bolt on.
[quote]

I know this, let me tell you what the rep at greddy told me, he phrased it kind of funny. He said "these turbos are completly Plug and play"
he said these turbos will run great on stock injectors and stock intercoolers with 50 hp gains, BUT he said do not use a boost controller (i did had no problems always ran 11:1)

and for the problem!!! i found it and you where wrong and of course i myself was wrong... i took some time to think because i knew i was skipping over 1 key element and it was bothering me... it finally came to me... BARO...
barometric pressure sensor, this is very important to a stock ECU on a turbo charged car of course, it tells the fuel map what boost you are running and from that it reads on the map to tell what ammount of fuel must be supplied to support it. now if this sensor itself went out or wires burnt up the ECU would correct itself and make the system lean. but what if by some chance the vacum line running from the manifold came undone or yet cracked or got cut in some way, it would read neutral all the time, no vacum no pressure, this of corse was the exact problem, just as i predicted, i looked under the hood and found that my freind was sloppy with his new Hose kit and had the vacum line dangleing down on the exhuast housing and it melted through.

problem solved car runs abosolutly find idles fine, and under boost runs 11:1 (stock injectors :P)

I still think you are boosting past the range of stock injectors. I think you are playing with fire.

The BARO sensor is built into the MAS/MAF. Im not sure which line you plugged back in, but I dont think it was BARO sensor.

96+ have a map sensor, which is as close to BARO as I can think of that might have its own line. But I dont know if it does for sure, I think its just bolted to the plenum.

Either way, I named 3 things in my first post. MAS, injectors, and o2 sensors.