SR20DET swap gone bad... any suggestions?

[AadosX]

Ok after working a couple things out, the car basically just sucks. It's very slow, maybe 16.0 1/4 mile. The O2 sensor I think is bad, so I ordered a new one, but that can't actually cause these problems. The car makes full boost, but just runs like shit. As far as I know all the coil packs and spark plugs are good. The MAF seems good. I replaced the fuel filter and soon will replace the fuel pump (but that shouldn't be the problem). I get horrible gas milage, BUT the car runs lean, very lean. When at full boost/throttle in high rpms it runs pretty good though (mixture wise), but its still very slow. We ran the ecu check to find codes and two came up. TPS and some auto tranny code, but I think that's nothing because its an S13 into an S14, with an auto to manual tranny swap. We hooked the voltometer up to the tps wire on the ECU and its giving a constant 4.95 volts, then at full throttle its only like 5.05 volts, so we're pretty sure that's bad. We have a new ECU and TPS coming in, and we're hoping that will do something, but I just dunno. Oh, one other thing... when I replaced the fuel filter, there were three hard lines coming from the rear of the car, but one of them just isn't being used... the other two obviously go into the fuel filter... what's that other one for? Some COMPLETELY incompetant shop named Augusta Customs installed this car, and since day one it has been a nightmare. This is where I am now though. Help please!

What do you guys think? I'm getting pissed off here.

[HiPSI]

if you're getting only 5 volts at the ECU then i'd suspect a problem. first thing to try would be the ECU/TPS, check all the wiring for being correct, etc. my friend's car was having voltage issues at one point (only getting 10v or so) and the car ran like crap (rich as hell in his case). ever since he hard wired a power wire to the ECU with a switch on it it runs great. this is with a redtop in an S13.

[christopher]

Did they offer any kind of warranty on their work? I'm guessing not since you are taking this into your own hands. First off, I would see if they could fix their poor work at no cost to you. If they can be held accountable for their work you won't have to pay for parts.

[AadosX]

I got the car back one time and it was shitty as crap. So I took it back and now that I have it again, it's worse than it was the first time. Sure they'll 'fix' it, but they don't actually fix it. I'm taking matters into my own hands and currently speaking to lawyers. Anyways, I need help getting this crap fixed... thanks.

I thought the voltage going to the ECU from the TPS was supposed to max out at 5? That's just what I was told... anyone esle?

[HiPSI]

I thought the voltage going to the ECU from the TPS was supposed to max out at 5? That's just what I was told... anyone esle?


oh sorry, i thought you meant the ECU supply voltage. :bash:

[HiPSI]

oh and the 3rd hard line from the tank should be the one that goes to the charcoal canister (which is usually deleted on SR swapped cars)

[AadosX]

Awesome, that's what we were thinking too, but we weren't sure. I called Heavy Throttle and they had never even heard of a charcoal canister.

But I want other ideas/opinions too, keep 'em coming guys.

[TwoFourO]

Have you replaced the fuel pump with a 300z or Walboro unit? I know that before I replaced mine(with a KA though) it ran like complete ass having the same symtoms you are having. I replaced it w/the Walboro unit and the car has run like a champ for over a year now w/no problems. Good luck.

[AadosX]

I'm about to order the fuel pump, but I can only hope it will be something as simple as that.

[Redtop_240]

Cant say I could add anymore addvice to this story........I think its all been covered other than, maybe a bad ECU and a timming issue......

[Natty]

I was gonna say fuel pump/fuel filter/ecu/timing, but that's all been covered? It has the right plugs, right?

[AadosX]

As far as I know, I bought some more plugs so I may try those out. Oh yeh, if I forgot to mention it, we thought they messed up the timing, but we got that checked out and its a-ok.

[DRFT]

a little OT but im not familiar with the turbo terms rich and lean, i heard of it many times but never got an exact idea on what it means?

anyways hope you figure out your problem

[AadosX]

Wow, and with 2k posts? What do you usually work on... I'm assuming suspension etc. Anyways, I'm not making fun or anything. Rich is basically not enough air, and lean is too much air.

[DRFT]

ok thanks

hehe most of my post are just BS post, and all day bordem

[AJs14]

Coil packs?

[AadosX]

Is there a way to test those? I was thinking the same, but I figured the engine wouldn't even hardly idle if one was bad.

[oberkill]

Disconnect the coil packs one at a time. Basically:

(Car is off at this point)
disconnect #1 coilpack
start car.

if the car wont start or runs worse than that coil pack is fine.

shutoff car.

repeat with each coilpack, if you hit one where there is no differance with it connected or disconnected then either the coilpack or the plug or that cylinder is faulty.

You might also try this with the injector plugs. You could have one injector that is faulty and either flooding the cylinder with fuel or not putting out enough fuel.

Alan

[AadosX]

So it's ok to start the car w/an injector or coilpack unplugged?

[mjjstang]

well When you run a compression check, your running only 3 cylindars at a time, so Id assume its safe, and everybody runs compression checks.

[AadosX]

Hrmm, true. But I don't know how these coilpack ignition systems work. I know that you couldn't run a comp. test on my last car w/out it going crazy, it was a 2000 BMW and some angle sensor thingamabob I dunno.

[rednerd]

Okay. If your TPS is putting out 4-5 volts it is either bad or needs adjustment. The tps should put out almost 0 volts with the throttle close and 5 volts at WOT.

If you are running lean my guess is that all of your coils are good. How do your plugs look? They should be a little red at the base of the ceramic and white or grey towards the tip.

Clean your MAF and check your base timing. You have correct ecu right?

Check for vaccum leaks. You should be pulling aprox. 20 in/hg (steady) at idle.

[rednerd]

a little OT but im not familiar with the turbo terms rich and lean, i heard of it many times but never got an exact idea on what it means?

To elaborate on what someone else said. Gasoline burns most efficiently when metered to 14.7 parts air. This is refered to as the stochiometric (sp?) ratio. Your ecu will try to run at this air/fuel ratio when the engine is warm and you are cruising. The ecu reads the O2 sensor and plays with the fuel to try and keep the O2 voltage between 0-1 volt. This is why most stock O2 sensors are known as narrowband, they only read when the AFR is close to 14.7:1 (oh yah and those cute autometer afr gauges will get you laughed right off a dyno). Under acceleration the ecu doesn't look at the O2 sensor (pre-OBD-II cars) it reads the TPS voltage, water temp, and AFM voltage (which is probably why his car runs better at WOT because the TPS voltage is closer to the correct value).

If the engine is using >14.7:1 AFR it is sucking too much air and causing the fuel to burn to hot. This is really really bad. This is where you burn valves, pistons, and detonation will occur. For safety sake under load most cars are tuned to run rich, <14.7:1. In fact I believe Nissan tunes their SR ecu's to about 9:1 at high rpm and WOT. Most tuners lean out this area to 10 - 11.5:1. Most people who tune themselves shoot for 11 - 12:1. Unfortunately, any greater than 12:1 is running the risk of leaning out and causing engine damage should an injector get dirty or a fuel filter gets clogged, or the AFM fucts up.

Sorry for insomnia induced the off topic post jack.

[the head]

what ecu are you using

[AadosX]

I'm using the auto ecu. It's an S13 in an S14... I'm assuming the S13 SR ecu is in there.

[russian]

your problem is in your Ecu. you need to find one from a manual, without errors. :squintd:

[rednerd]

your problem is in your Ecu. you need to find one from a manual, without errors. :squintd:

Not likely. The difference between the two ECU's is minor and in software. I have a "tuned" #63 ecu. It was just reprogrammed with a bin that had the limits removed on a #62 bin.

Your ecu is a #63, right?

[fliprayzin240sx]

EH...how the hell can you use a AUTO ECU with a 5-speed????

[rednerd]

Nissan (at least pre-OBD-II) uses a seperate ECU for the engine, transmission, ABS, HICCAS, and even the seabelts. There are three wires that go to from the AT harness to the ecu, basically gear positon and TPS kickdown.

I actually have a "professionally tuned" ecu that is simply a #63 ecu witha #62 progam and the limits removed... Don't get me wrong, having an automatic ECU will slow the car down because of the retarded ignition map, but if he has a bad throttle position sensor it will run like crap no matter what ecu he has. The TPS is simply a potentiometer so if it is fuct it will respond the same way irregardless of what the ecu.