.db.

month or so ago I bought a sr20 front clip from phase2motortrend. I picked it up and was told it appeared to be a type x black top but the valve cover had been changed. It does have the fins on the front of the head and has a J4 ecu. However little things like the o2 sensor suggest redtop. Is there any way to determine for sure what my motor is?

since my swap - I ran stock o2 housing with about 3 inches of downpipe. Ran fine - But would bog down coming off a hard accel. really similar to how people with atmospheric bov cars run. But mine is all stock. Has boost controller to raise to factory 11psi. Figured it was iacv.

I recently installed my isis complete exhaust turbo back. figuring it was a black top so I didn't order the o2 sensor adapter. When installing I found that I actually had a skinny o2. I did some research and a few guys on zilvia said a fat o2 from a z32 tt would work. So I went down to the parts shop and got myself an o2 sensor. 3 wire sensor - 2 white and a black. Did some research the red and white in my factory harness were heater circuit and the black was the signal. Anyways. I installed installed the sensor and exhaust and ran how it did before only quieter. Put 200 miles on it and it started acting up.

Runs great when it's cold. Soon as it warms up it misses a little. now it bounces from 500rpm to 1500rpm at idle runs very very rich and misses a lot. I've verified fuel pressure without vacuum at roughly 44 psi - 35ish with vacuum applied. It does respond to throttle. It also holds fuel pressure for at least 30 minutes after shut off. I also checked my plugs. They have roughly 1000 miles on them and are carbon fouled. I cleaned them up and verifies gap at .030". Reinstalled. Cleaned IACV and MAF, verified resistance in injectors at 11-12ohms. Cleaned pcv valve and verified operation.

I am waiting for my o2 sensor adapter to reinstall my old skinny o2 sensor - it will be here today. I removed my air filter (cone) to see If that is restricting flow. If the problem continues I'm going to use the smoke machine at work to fog my intake and see if I have any leaks and try checking for a boost leak all though I'm not super sure how to go about it. I don't have access to a timing gun but I can verify timing marks.

Sorry for the novel - I really want my car to run smooth. I'm only getting 175 miles on 13 gallons. It's killin me. If anyone has ideas. I've been searching for the last week for forum posts about this. I've checked nearly everything. was hoping to get some insight.

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.db.

Also my boost gauge reads 19hg at idle. Don't know if this is normal.

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Kingtal0n

The skinny O2 sensor only came on redtops. It sounds like a redtop from 91-92 that somebody installed a type-x harness and ECU on. The skinny O2 sensor will not work with the J4 ecu iirc. You need to run the typical fat O2 sensor for best results.

That could very well be the issue regarding your fuel economy. Two things you need to do next are:

1. Boost leak checks (do this often) Fill the plumbing with about 15psi of air pressure and check for leaks. This is the #1 most often overlooked issue with these engines.

2. Get a normal size O2 sensor wired in properly. use the J4 diagram (I made one a while back, just google "62 to J4" and it should show up) to wire the signal wire to the ECU. Do not worry about the other wires right from the start- JUST wire the signal wire. Once you see the sensor voltage working (flipping) if you do not know what that means ask. THEN wire up the O2 heater.

O2 sensors only need 1 wire connected to work. Even if they have 1, 2, 3, or 4 wires- Its just ONE signal wire to work. In fact, you can goto pep boys, and buy ANY $12 1-wire oxygen sensor from the shelf and it will work fine.


Finally,
a. your idle vacuum is normal. That is healthy valvetrain to pull that vacuum. If you just got the engine make sure you do a compression test, and WRITE DOWN the results. Compare with those results after about 5,000 miles. You may want to run some de-carbonizing fuel additive through it a few times. Or some distilled water through a very tiny nozzle over the course of a few thousand miles.

b. change the pcv valve, they are easy to change and cheap
c. get a brand new set of cheap NGK plugs for the engine with a 7 heat range, that you will install ONLY after you fix your rich running problem. For now, disconnect the oxygen sensor until you get that sorted out.

__________________
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https://tinyurl.com/turbo240

.db.

okay so i changed the pcv valve for the h of it.

I installed the original o2 that came with the car. It ran great for about 2 days. I was on my way home and it started running rough - even getting what seamed like fuel cut at 3200 rpm or so. The car would lurch and wouldn't go any faster.

I tested my TPS sensor, thinking it may be the cause. i have 5v being delivered and when i resitance check the sensor it self at fully closed i get 11-12 ohms. When its open I get 5-6 ohms. According to the FSM I should see 0.35-0.65 ohms at closed and 4.0-5.0 at wot. I am testing between (B) and (C) terminals on the sensor as directed by the FSM on EC-204 and EC-135.

My roommate said his coupe did the same type of thing, lurching, bogging, running rich, and he replaced his MAF and it fixed the problem. I am currently working on making jumpers to use to install the sohc maf from his car to see if anything changes.

The spark plugs i have before (installed when i did the swap) were 6 range. I installed the 7's but havent driven with it yet.

I have yet to do a boost leak check, however i did smoke the intake and did not find any large leaks. I did however find the vacuum line to the fpr to be brittle and it fell apart in my hands so i went and replaced all the vacuum lines.

Kingtal0n

A. if you think the tps is causing problems, disconnect it. The engine should run fairly normal without it connected on a stock sr20det.

B. Disconnect the oxygen sensor if you think it is causing problems. The engine will run normal without it connected.

C. As to the maf, if you have a redtop, #62 ECU or E5, you can use any SOHC KA24E Maf sensor hotwire in place of it. You should be able to find one of those cheap or easy. I used to carry a few spares in my glove box. Just grab the hot-wire (2 philips screws) you dont need to buy / replace the entire metal housing.

You can also try cleaning the maf hotwire.

__________________
5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

.db.

I have a J4 ecu and my head has the fins on the front typically found on the blacktop so i thought it was a blacktop with redtop valve cover - but my o2 sensor was a redtop skinny - so i was a bit stumped there. I will try unplugging the tps next time it acts up - will it be in limp mode then?

Kingtal0n

The point is to see how much, if any, difference it makes, when you unplug something. If you pull off the TPS and nothing changes... then the tps probably wasnt causing the issue.

Like I said already - try to use a 1-wire O2 sensor. Buy the cheapest ($17) 1-wire from pepboys and wire it to the signal wire and be done with it.

__________________
5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

.db.

I have a known good innovative lc1 wideband that has a narrowband sensor i'm picking up from a co worker this week and I'm going to try that. I have confirmed the TPS sensor is working normally at this time - 0.40v at closed and 4.06v at wot.

When unplugging the MAF nothing changes initially but when i plug it back in the car almost dies, catches itself and returns to running the same. All the fuel injectors respond to being unplugged, same with coil packs. I don't notice any difference when unplugging the o2 sensor.

Having the j4 ecu - i've discovered its quite the PIA to diagnose things due to not having a diagnostics knob. I feel like im chasing so much pointless stuff. I've read a knock sensor could cause rich mixture, a coolant temp sensor could cause a rich mixture, the obvious ignitor chip etc.

I don't understand why the car ran fine with this o2 sensor before but isnt running fine with it now.

Is there anywhere that explains what sensors may effect fuel trim and in what way? I'm running out of ideas.

Kingtal0n

The J4 uses a standard O2, and the wiring is different on the plug for the skinny-type sensor. If you just plugged a skinn-type sensor into the J4 harness you may have damaged the ECU.

Just leave the O2 sensor unplugged until you sort out your issues. You did not mention whether it helped to be unplugged or not. The SR20DET will run fine, not RICH, for years without the o2 sensor plugged in and get great fuel economy.

Did you ever perform a boost leak check, because this is the #1 most important overlooked aspect of sr20det running rich diagnosis.

__________________
5.3/4l80e/turbo 240sx playthrough:
https://tinyurl.com/turbo240

.db.

I finally got the stuff together to do my boost leak check. Found my intercooler to be leaking a lot. Haven't driven car with o2 unplugged. That's next. Have to wait a couple weeks to order a new intercooler. Lol.uploadfromtaptalk1399127457106.jpg

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ultimateirving

Your symptoms to match up with a bad vac leak, bad mileage poor drive ability.
Boost leak test will help to find them all. And I would recommend doing them semi frequently on turbo cars.

Also the tps should be tested by the voltage. Around .45v at idle and no more than 5v fully open(car doesn't have to be on to test the wot setting)

__________________
Z32 with lq4 swap
Desert Street Scene || Dssevents.com

JF_OverBoosted

Pretty much what ^ said.

__________________

.db.

Okay so I finally got my front mount in and put on. I did a leak down from intake on. Found a few leaks and fixed them. Still have a small leak before the turbo after the maf where the recirc hose would have gone. My cap isn't sealing quite right. Put 30 miles on it yesterday and had no problems. This morning I'm driving into work and it's running rich again sputters around 4k rpm... i have some wiring issues at my ecu I'm going to fix on my lunch today. But are there any other suggestions? I'll recheck the tps while I'm here with proper tools. The only other thing I can think of now is maybe the vta bov is causing it? Idk I feel like the ecu should be able to adapt to that tho. Isn't bogging at idle or dying.

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awesomestmonkey

Okay, sorry for the account change, I'm using my roommates laptop to post this (from .db.)

I performed a test on my ignitor as someone suggested it on another thread. My results were... odd. Where I expected to have no continuity, I had continuity, and where I expected to have continuity, I had none. I triple checked my work because I was thrown off from these results.

I used the diagram from the FSM stating between "E" (G on my ignitor) and 1, 2, 3, and 4 with the positive lead on "E" and negative on the # I should have no continuity. I had 17.4 ohms on each terminal. Reverse the leads, I should have continuity and I show infinite.

Between "E" and A, B, C, and D I should have continuity and I do, 1.5 ohms on each terminal.

Between 1 and A, 2 and B, 3 and C, 4 and D with the positive lead on the # I show infinite where I should have continuity. Reverse the leads and I have 17.7 ohms across the board..

I am stumped by this. Anyone have insight?

.db.

The test I performed:
Attachment 72490

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.db.

uploadfromtaptalk1403149731380.jpg

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ultimateirving

Ignitor a are pretty easy to replace. Find a friend you can swap with or go to a junkyard I think the q45 ones are the same

__________________
Z32 with lq4 swap
Desert Street Scene || Dssevents.com