Texarkana: My RB20DET truck is slow :( some ideas please??

[s13_240_rb20]

My RB20DET-swapped pickup is slow. It was a very educational experience swapping this in and making the necessary mods. I barely got through it..lol.

Vehicle:
1993 Nissan D21 Hardbody pickup
Engine: RB20DET from a 1993 Nissan Skyline GTS-T
Trans: stock RB20DET's trans
Rearend: stock automatic Hardbody rear axle 2wd (take note I said automatic, I think this is my problem)

Minor Mods:
FMIC
Walbro GSS-342 Hi-Flow fuel pump (fuel pressure is consistent and rises when throttled)
Nismo FPR (set to ~40psi at idle, ~43psi at WOT)
XTD stage 2 clutch and pressure plate

Also:
Fuel pressure gauge
boost gauge

Known problems:
1. speedometer is not working due to incomplete wiring (due to frustration)
2. Nissan datascan is not completely wired (due to wiring frustration) so no help in troubleshooting
3. I think my o2 sensor by the turbo is bad, if I remember correctly, but it still made great power when the engine was in my 240sx.
4. My throttle position sensor (TPS) is not precision tuned. It has been free-hand-adjusted and test-driven to maximize performance in this condition.
5. My Crank Angle Sensor (CAS) is not precision tuned. Same reason as the tps.
6. My BOV has both vacuum hoses plugged off b/c someone told me it was leaking vacuum (??)
7. Although new when I built this a year ago, the clutch is excessssively noisy when driving or neutral. Noise silences when clutch is pressed in.

Description of performance:

1. Hesitation when I engage 1st gear from a stop. I have to re-clutch and then re-gas it b/c it seems to be so weak at the wheels that the engine would rather stumble.

2. 1st and 2nd gear are weak but perform rationally: Low rpms (under 4000) seems weakest. Around 4k rpms, the engine starts sounding like a performance engine (engine purrs, turbo is whistling, exhaust sounds great) and the performance is at its best (truck accelerates enough to pass other cars on long straights)

3. 3rd gear gets weaker. I would only dare to pass someone doing that is doing 60mph on the interstate so I don't run out of time and hit oncoming traffic. It will speed up to around 4500rpms, which feels like 70mph.

4. 4th gear seems to make almost 0 power. I may be able to speed up to about 75mph at about 4000 rpms at full-throttle.

5. 5th gear feels like it makes completely 0 acceleration power. 5th gear at full-throttle barely maintains around 80mph at about 3000-3200 rpm. If I stay full-throttle for a mile or so, I think I hit around 90mph at 3500rpms (max).

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This engine/trans HAULED $&*# in my 240. The only thing that comes to mind that is mechanically different and the rear differential and aero-dynamics. I have replaced the walbro pump in case it was dry-rotted during the swap, and replaced the NGK spark plugs. Fuel pressure at the rail seems perfect.

I hate re-clutching just to leave a stop light. What's up with that?? I even have to re-clutch if I rev high enough to chirp the tire.

As for the rear differential, I have been searching and the Nissan hardbody seems to have a gear ratio of 3.7 (not confirmed) and my r32 vlsd I had in my 240 was a 4.36. According to the net, "HF37 - H190 axle found in weenie 2wd Frontiers" but my 1993 Hardbody doorjam sticker says HF37 (??).

Anyways, if that info is right, is it possible that my differential cannot spin fast enough or WTH is going on????

In summary, I can't launch because it stumbles at launch and I have little/no power past 5k in low gears and no power at even lower rpms in 3rd, 4th, and 5th!!!!

Please give me allll possible feasible ideas!!! I need help on ANY issues you can detect. I will follow troubleshooting advice as best as I can, if I have the tools and understanding.

Thanks for reading this BOOK!! I am moving to Texarkana, AR/TX, in a month or so if anyone is from that area, I would love any help I can get.

--TJ

[Gold Digger]

Moving this to RB forum as you'll probably get some actual help over there...

[l0nestar]

Fix the known problems first. (e.g. CAS, consult, o2, BPV, etc.) then worry about performance.

If you can't figure out how to count the teeth in your 3rd member.. yikes..
(here, I'll do the hard work for you. it's 39 and 11 (ring and pinion). H190 == 3.7:1 open diff.) It was only the first hit on Google.

Gogolinsky has a good description of available differential combinations. http://www.that dead forum/hb-truck/15 ... ost1268380

[mixeds14]

agree...^^^^^^^^^^^^.............

[s13_240_rb20]

With all sensors being the same as when I had when it was in the 240sx, it was still fast in the 240sx. The only different component is the rear end so I posted the following, which explains the difference between what I found when I already searched and when I checked my vehicle:
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As for the rear differential, I have been searching and the Nissan hardbody seems to have a gear ratio of 3.7 (not confirmed) and my r32 vlsd I had in my 240 was a 4.36. According to the net, "HF37 - H190 axle found in weenie 2wd Frontiers" but my 1993 Hardbody doorjam sticker says HF37 (??).
--------------------------

Soooo, can anyone provide me some direct input on where I should start to see the most improvement?? such as, for example only: "If the CAS is advancing your timing too much, it will limit the top end revs b/c it floods out" or "the H190 axle isn't capable of spinning as fast as the RB20+trans are trying to turn it, thereby physically limiting how high you can drive each gear"....

I have a million possible ideas on these problems but I am an amateur and would like some detailed advice from people with experience, because I do NOT have a million dollars to go through replacing EVERYTHING just to hope I find the biggest problem: limited top revs and top speed.

Thank you for any experience you can share with me.

--TJ

[l0nestar]

Are you retarded or just plain stubborn?

Fix the wiring so you can read consult data which will allow you to verify or 'precision tune' as you call it, both your CAS and TPS. If both aren't correct, it will give similar symptoms. I.e. your ECU doesn't know where it is (timing wise) and you can't decide which map to pull from.

Bosch 11027 - Single wire Universal oxygen sensor: $17.99. Shouldn't break the bank, connect it to the center pin (signal) on your existing o2 harness or connector.

SO again, fix your known problems which will alleviate and remove them from possibilities.
It's the second step in troubleshooting, eliminate the first item that will yield the greatest benefit.
Followed or sometimes preceeded by 'If you experience an MIL (Malfunction Indicator Lamp) or in this case, errors or known problems, resolve them before proceeding.'

[RustspecS13]

A rear end ratio wont limit anything relating to the engine. It only changes the power the rear wheels see.

That should be the majority of your speed difference. Also the trucks weight. I would actually fix all your known problems, and try to find a 4:1 rear end for your truck, or a 4.4:1 similar to what you had and go from there.

~Alex

[ItzGenX]

Ok I didn't feel the need to read through the whole thread after I read down to where your fuel pressure is set at. You mentioned WOT and idle settings, which are both not really relevant. The fuel pressure should be set with a 1:1 rising rate fuel pressure regulator to 3 bar (43.5psi) with the vacuum hose OFF and fuel pump running. If boost is set to 7psi, your fuel pressure should be reading 50.5psi with WOT during full boost. If all you see is 43psi peak, then you are not getting enough fuel.

[s13_240_rb20]

Thanks for the tip on the Bosch sensor..I will go look for it now. I troubleshooted the datascan wiring before and never located where one of my wires is losing its signal. I will try again when I get time.

A rear end ratio wont limit anything relating to the engine. It only changes the power the rear wheels see.

That should be the majority of your speed difference. Also the trucks weight. I would actually fix all your known problems, and try to find a 4:1 rear end for your truck, or a 4.4:1 similar to what you had and go from there.

~Alex

but since the truck is a 3.7, at XXXX rpms, I should be going faster in the truck than I did in the car. It's weird because it feel slower on acceleration and limited on top rpm power. I will try the cheaper things and see what happens before I resort to rear-end swaps.

[s13_240_rb20]

Ok I didn't feel the need to read through the whole thread after I read down to where your fuel pressure is set at. You mentioned WOT and idle settings, which are both not really relevant. The fuel pressure should be set with a 1:1 rising rate fuel pressure regulator to 3 bar (43.5psi) with the vacuum hose OFF and fuel pump running. If boost is set to 7psi, your fuel pressure should be reading 50.5psi with WOT during full boost. If all you see is 43psi peak, then you are not getting enough fuel.

So because I assume that my nismo fpr and brand new walbro are good, do u think my vaccuum is not properly pulling up my fp??

--TJ

[ItzGenX]

You never specified how you set your fuel pressure. When setting the fuel pressure, the vacuum hose should be removed from the FPR. If it is set to 43.5 psi, you should be seeing a lower number during idle with full vacuum (and the vac hose attached). The amount that it lowers by is the same amount that is being pulled on the vacuum gauge. So at idle, 0% throttle, your fuel pressure should be 43.5psi minus vacuum pressure. At wide open throttle during full boost, it should be 43.5psi plus the boost pressure. If you are not seeing more than 43.5psi at wide open throttle during full boost, you are probably running lean if the injectors are not tuned to run with that low of a pressure. Your vacuum source should be a source that can see full vacuum and full boost at the intake manifold after the throttle body.

[s13_240_rb20]

You never specified how you set your fuel pressure. When setting the fuel pressure, the vacuum hose should be removed from the FPR. If it is set to 43.5 psi, you should be seeing a lower number during idle with full vacuum (and the vac hose attached). The amount that it lowers by is the same amount that is being pulled on the vacuum gauge. So at idle, 0% throttle, your fuel pressure should be 43.5psi minus vacuum pressure. At wide open throttle during full boost, it should be 43.5psi plus the boost pressure. If you are not seeing more than 43.5psi at wide open throttle during full boost, you are probably running lean if the injectors are not tuned to run with that low of a pressure. Your vacuum source should be a source that can see full vacuum and full boost at the intake manifold after the throttle body.

Thanks for specifying about the vacuum source. It comes from directly under the FPR so tomorrow I will verify its source on the manifold. I have noticed that, when idling, I show very very little/if any vaccuum on my gauge which is tee'd in at the back of the manifold. It usually idles right at 0 vac/boost. And, yes, I see only a few pounds of increased fuel pressure when at 6-7 lbs of boost. seems rare for me to get the full 7 lbs of boost when I am flooring it through the gears. I always easily get 5-6 but rarely a solid 7.

--TJ

[Carl H]

reading this you need to sync your tps as well as your cas to spec...with an rb20 even 5* less timing than spec will cause serious drivability issues.

[s13_240_rb20]

If the FSM tells me how to set the CAS and TPS with a voltmeter, I will have no problems adjusting them.

I do see the 7lb increase in fuel pressure at WOT now... I will set fuel pressure exactly per spec...right now I am running about 45 (with 0 vac at idle) and it goes up to 52. It just seems to run better set that high with these incorrect settings.

Speaking of which: I have 0 vac at idle...never any suction.lol But I now see the full 7lb's of boost after some more incorrect tweaking....

I will set them when I can find the dang time.

--TJ

[RustspecS13]

Stock RB20 boost is 10psi and stock rb25 boost is 7psi.

You might want to check for a boost/vac leaks.

~Alex

[s13_240_rb20]

Stock RB20 boost is 10psi and stock rb25 boost is 7psi.

You might want to check for a boost/vac leaks.

~Alex

10? you're kidding, right?

[themadscientist]

No, he isn't. I've owned several of the model Skyline your engine came from; factory boost is .7 bar, about 10psi.

[Carl H]

you cannot check timing with a volt meter, you have to use a proper timing light.
you should also have approx 20in/hg of vac. at idle with a stock rb20, if not then your gauges is either a) not on a proper vac source or b) you have some horrifically bad vacuum leak.
my vote goes to a.

[RustspecS13]

10? you're kidding, right?

Not really no. And guess what, don't go over 13psi either. The ceramic exhaust wheel likes to disintegrate because its old and fragile.

I'm not kidding about that either.

~Alex

[s13_240_rb20]

10? you're kidding, right?

Not really no. And guess what, don't go over 13psi either. The ceramic exhaust wheel likes to disintegrate because its old and fragile.

I'm not kidding about that either.

~Alex

Hmmm....ok...ok..I have got some serious learning to do then. And then alot of doing. Using this vac source, I once had -2 for vac at idle. just not anymore since I went stupid during this swap. I have my boost gauge "tee'd" in somewhere at the firewall area.... Does it matter that it is "teed" in, hence sharing vac and boost with another destination besides my gauge? Or does it need its own designated source?

One day soon I will take a look at it. I am off on Tuesday but I am hoping to go sign papers on my house . Once I sign those papers, I may worry more about moving than tweaking it, because I don't want to make it undrivable when I am about to move an hour away :O....

Thanks all!!

[s13_240_rb20]

Ok...so...On Wednesday I got done workin on my other stuff and worked on the Hardbody:

I can't seem to get the idle down from 2k rpms with everything set right, and if i turn the aac to drop the idle, the engine lopes up and down and usually dies. Other than that, at a warm idle, I:

--set the tps at .4v
--using a spark plug wire between coil and plug, set the timing at the 3rd notch (10 degrees) at the very top dead center of the pulley because I am a dummy and counted it wrong...I wasn't paying attention
--set the fuel pressure at 40lbs again because it seems to have changed.

everything seems to change everything else: aac, tps, fuel pressure, and even timing....if I change one it seems to throw off the others and I have to go through them again. This running in circles jerked me around and I overlooked my timing mistake.

I now have power in 1st through 4th gear, up to 5500rpms.
My fuel pressure still rises correctly with throttle.
My CAS is turned completely counterclockwise....probably because I am at 10 degrees instead of 15 degrees.


However, instead of 7lbs, I seem to top out at around 5lbs of boost now.....and am I really supposed to have 10lbs? I have always had 7lbs. I am tee'd in between a vein from the intake arm and the nipple on the back of the manifold (on the pass side of the engine at the top).

I will reply again in a few days when I am off and have a chance to correct my timing and then retune the fuel pressure, aac, and tps since all the voltages seem to change. But I am willing to bet $$ that I will still get nothing higher than 7lbs...

[s13_240_rb20]

I went on down to the autozone and picked up that Bosch 11027 o2 sensor and put it in today. I have not started it since putting it in. I have been busy all night tonight trying to figure out why my consult is still not connecting. It worked when it was in the car, and I have gotten it to connect in the truck on rare occasions. I don't know if I have any intermittent wiring "opens" but I have double checked my wiring according the the info below, which is exactly how I wired it in the car and it worked conistently great...What am I missing? I have verified that everything matches as per the guide below, and I am getting voltages (from the ECU) at the cable-side of the blazt plug...

Any ideas on why it won't connect or what I am overlooking? My port and drivers are right, it just IS NOT showing the full ecu part number (which is when it can connect).........



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ECU Pin #____Signal Name_____Color___________Color on CONSULT USB
21___________RX_____________Yellow/Green Stripe______White
22___________TX_____________Yellow_________________Yellow
31___________CLK____________Yellow/Red Stripe________Blue
45___________IGN____________Black/Red Stripe _________Red
47___________CHK____________Yellow/Purple Stripe _________NOT NEEDED..believe it or not..

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[gmac708]

Check your TX and RX are not swapped. I made same mistake. It gets a little crazy with the wiring and adapters sometimes.
Here is link for Blatz troubleshooting, showing connector. Note: View looking into connector on vehicle(not from back side of connector).
http://www.blazt.biz/forum/viewtopic.php?t=320

[s13_240_rb20]

I just double-checked all my wiring and all looks right, just like I noted above. All have various voltages or ground where expected.

I keep uninstalling and reinstalling Datascan 1.3 and any drivers I can find. I keep ending up with "USB to UART..whatever" under ports, installed correctly. It is using "silicon labs" drivers. But I end up with a "universal serial bus (code 10, not working)" under "other devices." I cannot find any driver to match this "other device" and I cant even figure out what this device is....

I am using a blazt cable, Datascan 1.3 and windows xp...can anyone check their setup and tell me how their's looks in Device Manager, and what driver files they are using?

[gmac708]

I'm running Data Scan v1.52
I have the USB adapter. I'm at:
COM Port 5
Port speed 9600
Address read command (in Hex) C9
ECU Id (in Hex) EF
checked box for Auto connect to ECU


I usually have to plug USB in after engine ECU is powered up. Then I get the ECU part number confirmation.

Gord

[l0nestar]

Download the 'consult drivers' from Blazt site.