I have not ever really had to depend on Datascan to troubleshoot anything...ever. I am posting a pic of my datascan screen and I need someone to look at the readings and tell me why it feels like it is not tuned correctly. It feels like it is supposed to be more powerful. My RB20DET is now in a Nissan Hardbody pickup, and I pretty much "adjusted" EVERYTHING under the hood trying to make it start and idle before I found a couple of wiring errors. Now I have no idea which sensors are tuned incorrectly.

I have a very tight-feeling clutch pedal and a stage 2 clutch installed when I did the swap, but when I leave a red-light, I have to rev/clutch a few times and it launches sorrier and slower than my KA24 sohc hardbody....it isn't supposed to be like this I have to rev super high to spin the tires but even then it is a let down...

The readings you see in the picture at taken at IDLE.....I am most curious about my TPS, Timing, and Injection because those are the ones I "adjusted" back and forth. (and I am pretty sure my O2 sensor is not working...probably part of my powerloss due to running rich?











After turning the TPS down slightly and, more importantly, turning the CAS clockwise 1/2 of an inch or so.....It launches even worse, tends to backfire a little bit around 4-5k rpm, but it has better acceleration??? Here are the readings, at idle, after the two adjustments I just mentioned...



As you can see from before and after photos of the datascan software, I already know the TPS adjustment also dropped my rpms by about 1000rpm, and my CAS adjustment dropped my timing down significantly...

But what is the "perfect tune"?? For an idling RB20DET, what SHOULD these numbers be??????

Thanks,

--TJ

Don't use the data scan screen to adjust your tps. Break out the volt meter and set it to .48. Is the ECU in your car Auto or 5speed? Base timing should be set at 15 or 20 depending on the ecu. Check your fuel psi and set it to stock which I forget it is but a search should locate that. If it's idling too high adjust the idle air valve and check for boost leaks.

Yellow4g63 wrote:Don't use the data scan screen to adjust your tps. Break out the volt meter and set it to .48. Is the ECU in your car Auto or 5speed? Base timing should be set at 15 or 20 depending on the ecu. Check your fuel psi and set it to stock which I forget it is but a search should locate that. If it's idling too high adjust the idle air valve and check for boost leaks.

It is a 5sp, and the ecu has a sticker that says "Blitz" (or something like it...)

I don't have a timing light. Is there a way I can set the timing correctly by using datascan? If so, should the engine be off or idling, and what should the datascan timing reading be?

I will do that on the psi and tps...psi is typically 37/44, depending on vaccuum or not. I have noticed that my fuel pressure is going crazy on me, unless my cheap gauge/sensor are just that horrible. I can set f/p by using the gauge and within two days, I look at the gauge and f/p is up around 65psi. When I give it full throttle, my f/p jumps about 15-20 psi no matter what I have it set to.....bad gauge/sensor or is something adjusting my vaccuum (or anything) and resulting in higher fuel pressure???

I have spent way too long adjusting one sensor to make up for another side-symptom...I have been "robbing peter to pay paul" and now I have to set it all straight again.....

Also, you should not try to use my a/f ratio reading in my datascan pics....it doesn't ever move for some reason. Could a bad o2 sensor result in such oddball performance and high/unpredictable fuel pressure???

--TJ

And I don't even know how to check for boost leaks...My (also) cheap gauge tells me I idle at -2 and reach full stock boost at 7psi in a couple seconds....??

s13_240_rb20 wrote:

Yellow4g63 wrote:Don't use the data scan screen to adjust your tps. Break out the volt meter and set it to .48. Is the ECU in your car Auto or 5speed? Base timing should be set at 15 or 20 depending on the ecu. Check your fuel psi and set it to stock which I forget it is but a search should locate that. If it's idling too high adjust the idle air valve and check for boost leaks.

It is a 5sp, and the ecu has a sticker that says "Blitz" (or something like it...)

I don't have a timing light. Is there a way I can set the timing correctly by using datascan? If so, should the engine be off or idling, and what should the datascan timing reading be?

I will do that on the psi and tps...psi is typically 37/44, depending on vaccuum or not. I have noticed that my fuel pressure is going crazy on me, unless my cheap gauge/sensor are just that horrible. I can set f/p by using the gauge and within two days, I look at the gauge and f/p is up around 65psi. When I give it full throttle, my f/p jumps about 15-20 psi no matter what I have it set to.....bad gauge/sensor or is something adjusting my vaccuum (or anything) and resulting in higher fuel pressure???

I have spent way too long adjusting one sensor to make up for another side-symptom...I have been "robbing peter to pay paul" and now I have to set it all straight again.....

Also, you should not try to use my a/f ratio reading in my datascan pics....it doesn't ever move for some reason. Could a bad o2 sensor result in such oddball performance and high/unpredictable fuel pressure???

--TJ

Your fuel pressure is way too high. it should be like 42psi with the vacuum hose off. pop the top on your ecu it might have a different than stock program on it. Also if ur 02 sensor is bad usually it will show up when you check for the engine codes, But if it's not moving and just stays still then it could be dead. Pick up a wideband the narrow band stock 02 sensor shouldn't be trusted. You can should be able to put the car into timing mode by just unplugging the tps and starting the car after it's warmed up.

Yellow4g63 wrote: Your fuel pressure is way too high. ....... You can should be able to put the car into timing mode by just unplugging the tps and starting the car after it's warmed up.

Like I said, everytime I set my fuel pressure to 37/44psi it works its way back up to 60/65 in a couple days and I don't know why

Can you explain more about timing mode? I warm it up, turn it off, unplug the tps, and start it back up again?? If that is how I put it into "timing mode" correctly, then now what do I do? I don't have a timing light, so what should Datascan "timing" be set at for my 5sp?

Does adjusting the CAS actually set the timing or is it just "offsetting" the timing and not really fixing anything? I am so lost and need alottt of details/teaching..

Thank you

TJ

Your FPR is prob bad if it keeps climbing up like that. The Datascan timing display won't be the right mechanical timing best bet is to borrow a timing gun. Turning the CAS will advances or retard the ignition timing.

Yellow4g63 wrote:Your FPR is prob bad if it keeps climbing up like that. The Datascan timing display won't be the right mechanical timing best bet is to borrow a timing gun. Turning the CAS will advances or retard the ignition timing.

OK, so here is a question sooo dumb that you could easily quote it as your signature and make it haunt me forever: what is the difference between the "timing" and the "ignition timing"? And how are they related, because I have always just treated them like they were the same thing....when I adjusted the CAS I always assumed that I was actually adjusting the true "timing"....

But even if "timing" and "ignition timing" are the same....is there any major difference in performance in a perfectly "timed" and normally set CAS VERSUS timing that is off while the CAS counter-acted the off-timing??

Anyone in Arkansas want to come fix my RB?? lol I am truly a guy that doesn't even deserve it, yet somehow pulled together enough qualified people (when needed) and brought this truck to life....see the video at the link below:



or

click: http://s268.photobucket.com/albums/jj13 ... D00065.flv

--TJ

You need to get a timing light( they are pretty cheap and can be used on any car) Do a search or look in the FSM on how to set ur engine timing. The engine timing is a mechanical setting, the ignition timing is an electrical setting that the ECU sets. The actual timing of the engine is very important. The actual timing is when the position of the #1 piston in the cylinder. 15*BTDC(Before Top Dead Center) is where it should be. The ignition timing is when the ECU fires the #1 spark plug. If the ECU thinks the #1 piston is at 15*BTDC and it is actually at 30*BTDC or something u won't get a proper combustion burn. Set ur actual engine timing with a timing light and go from there.

ignition timing and mechanical timing are completely different

you cannot "counter act" mechanical timing errors. this is when a belt skips a tooth, or with adjustable cam gears the cam timing is incorrect.

ignition timing MUST be set with a timing light. period.

your FPR sounds like its junk if the pressure randomly rises

Thanks for the lessons, everyone!! I will check my mechanical timing with a timing light whenever the opportunity arises for a friend to come teach me one day..

Joe wrote:ignition timing and mechanical timing are completely different

you cannot "counter act" mechanical timing errors. this is when a belt skips a tooth, or with adjustable cam gears the cam timing is incorrect.

ignition timing MUST be set with a timing light. period.

your FPR sounds like its junk if the pressure randomly rises

Until then: My datascan "ignition timing" sits at 16 (no matter the position of the CAS) when the engine is off. If I remember correctly, it jumps to about 35 when the engine is idling and (??) is adjustable by adjusting the CAS (??). The datascan "ignition timing" increases and decreases with the throttle. Does anyone have a healthy stock RB20DET running datascan that can tell me their readings under those conditions: off, idling, and applying throttle???

As for my Fuel pressure: The fpr is supposedly a Nismo part so I am most likely to trust it. However my FP sensor/gauge setup is offbrand and my fuel pump is the weak little 4cyl hardbody pump. This leads me to believe that my sensor/gauge setup is not registering correctly b/c I lose so much power that the truck barely moves without stalling when the fuel pressure is set at 37/42 tonight.... It became so obvious to me tonight that my gauge is lying and that my fuel pump just isn't even keeping up with an untuned, low-power RB20DET, even though it never showed a sign of dropping fuel pressure.

Is there any possible explanation for my FP gauge NOT dropping when I am obviously running low on FP? Is there a certain amount of vaccuum that is constantly pulled through the fuel line when the engine is running, even if the pump isn't keeping up?

I know these are silly questions, but I miss the power I had when the RB20 was in my 240... I just don't have much time / money to spend on this project and get frustrated when I don't even know where to start... So I am starting by putting in my fuel pump upgrade and trying to get someone to do my timing.

Anyone know some simple upgrades that will increase torque or low-boost acceleration?? It sucks having to reach full boost to feel what little power I am making right now...

--TJ

Your going to kill that motor without a high flow fuel pump. Also some of those Nismo FPR have been known to be junk, might be a fake.

s13_240_rb20 wrote:Thanks for the lessons, everyone!! I will check my mechanical timing with a timing light whenever the opportunity arises for a friend to come teach me one day..

Joe wrote:ignition timing and mechanical timing are completely different

you cannot "counter act" mechanical timing errors. this is when a belt skips a tooth, or with adjustable cam gears the cam timing is incorrect.

ignition timing MUST be set with a timing light. period.

your FPR sounds like its junk if the pressure randomly rises

Until then: My datascan "ignition timing" sits at 16 (no matter the position of the CAS) when the engine is off. If I remember correctly, it jumps to about 35 when the engine is idling and (??) is adjustable by adjusting the CAS (??). The datascan "ignition timing" increases and decreases with the throttle. Does anyone have a healthy stock RB20DET running datascan that can tell me their readings under those conditions: off, idling, and applying throttle???

As for my Fuel pressure: The fpr is supposedly a Nismo part so I am most likely to trust it. However my FP sensor/gauge setup is offbrand and my fuel pump is the weak little 4cyl hardbody pump. This leads me to believe that my sensor/gauge setup is not registering correctly b/c I lose so much power that the truck barely moves without stalling when the fuel pressure is set at 37/42 tonight.... It became so obvious to me tonight that my gauge is lying and that my fuel pump just isn't even keeping up with an untuned, low-power RB20DET, even though it never showed a sign of dropping fuel pressure.

Is there any possible explanation for my FP gauge NOT dropping when I am obviously running low on FP? Is there a certain amount of vaccuum that is constantly pulled through the fuel line when the engine is running, even if the pump isn't keeping up?

I know these are silly questions, but I miss the power I had when the RB20 was in my 240... I just don't have much time / money to spend on this project and get frustrated when I don't even know where to start... So I am starting by putting in my fuel pump upgrade and trying to get someone to do my timing.

Anyone know some simple upgrades that will increase torque or low-boost acceleration?? It sucks having to reach full boost to feel what little power I am making right now...

--TJ

base timing and the timing you see in your datascan can be completely different also. THIS IS WHY YOU MUST USE A TIMING LIGHT TO SET YOUR BASE IGNITION TIMING ON RB ENGINES. your timing will move CONSTANTLY while modulating the throttle so stop worrying that it changes.

YOU NEED TO TIME YOUR ENGINE WITH A TIMING LIGHT

YOU NEED TO GET A REAL FUEL PUMP.

you WILL blow that engine on a stock pump if you arent careful.