My Latest...Injector leak and Exhaust Smoke

[tmorgan4]

I finally got my plenum to seat (one injector was in 180* off and wasn't allowing the plenum to sit flat). AFRs are now 10-12.

It started idling odd today after reaching operating temperature and threw an injector leak (code 45). I have a fuel pressure gauge that reads 50psi at 1100 rpm and holds a steady 35psi overnight with the engine off. Doesn't seem like an injector would be leaking...but how would the computer know anyway?

I also have a fair amount of exhaust smoke. It's white...like oil. Only happens when it gets up to operating temperature. I still only have 15-20 miles MAX on the engine....could it be that the rings still haven't seated completely yet? I hope I haven't fried anything already!

[Q45tech]

Injector leak code does not mean an actual injector leak just an O2 sensor that is reporting a bank rich for some reason............could be an aged O2 or high fuel pressure [43.4 psi is design max] or other reasons. A worn or nonstandard injector that flows more than others?

[T45]

You should drive it some more IMO. I don't have much exp with rebuilds but I do know that it takes a while for everything to get in order and the more you drive it the better it will run, and the better the mileage will get.

Not that you're concerned with mileage or anything...

[tmorgan4]

Makes a lot of sense. The O2 sensors I'm using are who knows how old and my injectors flow quite a bit more fuel than stock.

I decided it was probably a good idea to drive it around a little more and noticed that my wideband is actually reading leaner than I thought. Once it really gets up to operating temperature (driving for 10-15 minutes) it was idling at 14-16. I'm not sure what to think of this but there'a few possibilities:

1) Gauge/wideband is wrong2) Vacuum leak (idle is STEADY now, doesn't jump up and down like when I had a leak before)3) ?????

Fuel pressure is good. Can't think what else would be going on.

[SuperHatch]

Makes a lot of sense. The O2 sensors I'm using are who knows how old and my injectors flow quite a bit more fuel than stock.

I decided it was probably a good idea to drive it around a little more and noticed that my wideband is actually reading leaner than I thought. Once it really gets up to operating temperature (driving for 10-15 minutes) it was idling at 14-16. I'm not sure what to think of this but there'a few possibilities:

1) Gauge/wideband is wrong2) Vacuum leak (idle is STEADY now, doesn't jump up and down like when I had a leak before)3) ?????

Fuel pressure is good. Can't think what else would be going on.

From what I understand... You've installed larger injectors than stock, but have not tuned accordingly for them?

If that's the case, what size injectors are they? If they are not a whole heck of a lot bigger than stock, the ECU will adjust the STFT and LTFT to get the idle/cruise AFR's in line, however you will still be stupid rich at WOT. Scale the ECU for the larger injectors and then see what happens.

[elwesso]

what injectors are you running?

[tmorgan4]

Well it looks like the computer is smarter than me once again. My fuel pressure drops after shutting the car off very slowly. It goes from 35psi to 0 in about an hour.

I finally got a few hard miles in and it doesn't seem to smoke when I actually drive it. Good sign so far.

The injectors are supposed to be 370cc (all from Deatschwerks, phase 2 style) but on the flow sheet every one of them was over 400cc.

After driving it around it seems to be running really well, except it randomly cuts out and wants to die at the worst of times. It will run perfectly and as I'm accelerating or at a stop I lose all power. Starts up right away every time, though. I think it might be some electrical connections on the CAS and MAF but I've already bent the prongs and tried dialelectric grease.

[Stinky]

Fuel pressure drop can is more likely a small leak through your fpr or fuel pump check valve. Neither are a real problem as long as the fuel pressure is right when the pump is on. You should really clamp both the feed and return lines when you are trying to see if the injectors are leaking.

[tmorgan4]

The main reason I was thinking it might be a leaking injector or fuel rail is due to a couple reasons.

#1 the injector leak code, but this could be due to the higher flow injectors than the engine wants.

#2 when I had to rotate the #6 injector 180* in the fuel rail I tore the O-ring. I ordered a new one from Infiniti and $9 later it's the wrong O-ring. I accidently told them to look up a 94-95 part number instead of a 90-93 and the O-ring was about half the size of the one I needed. Being in a hurry I replaced it with one that I'm sure was right from an auto parts store's O-ring bin.

#3 Before I had removed this injector from the fuel rail it held pressure for a LONG time. One time I let it sit for 2 weeks, pulled a fuel line off and got a face full of fuel.

Either way, it seems to run pretty damn well right now. I'm not looking forward to pulling the plenum AGAIN but I want to get this running 100%.

Appreciate the discussion.

[tmorgan4]

Well I got a little better look at the wideband readings. I can't believe how much it flunctuates at idle. Normally stays in the 13-15 range and idles very smooth, but then it dips down into the 9-10 AFR readings and almost dies (and sometimes it does die) then shoots back up to 13-15 and goes back to normal.

What would cause these overly rich random scenarios?

[Stinky]

Sounds like a maf issue to me. Have you tried a different maf?

Really as long as their is a consistent maf and cas input there shouldnt be any significant change in afr at idle.

You best bet is to get a consult cable and software. With that you'll be able to see all the sensor inputs and see if they are acting properly.

[T45]

What about the ambient air temp sensor?

[maxnix]

The injectors are supposed to be 370cc (all from Deatschwerks, phase 2 style) but on the flow sheet every one of them was over 400cc.

That's normal. What is important is percentage of variation.

Might look at the integrity of hte ground of your FP through the FPCU. Might even exchange the FPCU for a known good one to diagnose.

[tmorgan4]

If the AFR should stay steady at idle something is definitely wrong. I think some of it could be attributed to the injector leak but the leak is so slow after the car is off I wonder how much fuel is really leaking past.

I bought another MAF a while back when I thought this one I'm running might be bad and it has been sitting on the shelf ever since. I'll try that one tonight.

I do have a consult cable and software installed on my laptop too. I can see what all the sensors are doing and check codes. I'm not getting a MAF code anymore but I used to before what I think was due to a bad connection. I cleaned up the terminals as best I could, used some diaelectric grease, and bent the prongs on the plug a little to try and ensure the best connection possible.

Has anyone hooked up a wideband to a stock VH45? I think I should be looking for a near stoic AFR at idle, right?

T45....there's an ambient air temp sensor?????????

Deatschwerks matched this set pretty damn well. The individual readings for "Static @ 100% IDC" in CC/min are 405,410,407,410,409,411,412,412. % difference is only .9%. Seems acceptable to me.

[T45]

yeah, I think on your pathy it should be up in front of the radiator. It's a lil round sensor with a diamond like mount. I know on the Z the wiring is separate from the factory engine harness so maybe on the pathy it's the same.

Honestly I don't remember hooking mine up either but the more I think about it the more it seems the engine would need it to perform optimally. Otherwise how would the ecu know how much air is flowing if colder air cools down the MAF quicker?

[SuperHatch]

AFR's do not stay steady at idle, you will see them swing rich/lean/rich/lean since the ECU is constantly trying to achieve a stoich AFR while reading a narrowband O2. Since the narrowband has such a small window of accurate measure the ECU constantly adds and removes fuel to keep the sensor reading right around that voltage point. This is normal operation on alsmost and EFI vehicle from the 90's, I wouldn't worry about that.

Also, you will not read stoich at WOT either. I'm not sure what the target AFR is for WOT operation on the VH, but I can guarantee you it's richer than 12.0:1.

[craigztoyz]

I pulled my Amb ait temp wiring, and before I have it up and running am curious if I should put it back in. What and how does it effect? Thanx

[Stinky]

If there is an ambient air temp sensor for the ecu it's news to me. The maf takes care of any air temp variations due to its design. If there is actually an ambient air temp sensor it's more likely for the ac system then the ecu. Although, I dont have much experience with the 94+ ecus so I could be wrong.

[SuperHatch]

If there is an ambient air temp sensor for the ecu it's news to me. The maf takes care of any air temp variations due to its design.

Explain?

[Carl H]

nissans use a hotwire maf which works on the principal of resistance increasing with heat.the ecu powers the maf and an internal wire heats up and as air passes over it, the wire cools and causes voltage to increase.because of this ambient air is 'measured' while the maf reading is taken.

[SuperHatch]

nissans use a hotwire maf which works on the principal of resistance increasing with heat.the ecu powers the maf and an internal wire heats up and as air passes over it, the wire cools and causes voltage to increase.because of this ambient air is 'measured' while the maf reading is taken.

I know how the MAF works...

This is my issue, and it's not with you, it's just in general.

GM and Ford use very similar MAFs as Nissan. 0-5V Hot Wire sensors. GM and Ford also use a separate Intake Air Temp Sensor in conjenction to the MAFS. Why? To allow for additional correction for extremely hot and cold climates and to verify the MAF accuracy.

90* air flowing through the MAF at X velocity will cool the hot wire Y degrees, and 40* air moving through the MAF an a velocity <X will also cool the air to the same Y degrees. You would like to think that the lower velocity cooler air (read lower CFM) would have the same Mass Flow Rate (read lb/min) as the higher velocity warmer air, but I'm not sure that's an accurate assumption. I could be wrong, but I just can't wrap my head around it right now.

On the Karman Vortex sensors typically found in Mitsu's the actualy air velocity is measured, the Baro Pressure is measured, and the IAT is measured to get as accurate an Air Mass reading as possible...

I guess I'm just fearing that Nissan has used a slightly inferior metering method than some other manufacturers.

[craigztoyz]

Thanx Stinky for the info. Thought Ambient was all for a/c, but always better to have the idea reinforced by others.

Is the pathy running better now? The oversized injectors seem to be running more then advertised, from what I read above. Can you componsate for it if it is running to rich?

[Carl H]

why would nissan's maf be inferior to other manufacturers?if you compare their ecu systems compared to other companies it wasnt until relatively recently that other manufacutures engine management even came close to what nissans's eccs offered when debuted in 89.not bad for a system that was most likely designed in 85.

[tmorgan4]

I switched out the MAF with my spare and guess what...it runs like it should. I haven't had it cut out since. My wideband seems to have an error since it doesn't budge from 22.4 again when the factory O2 sensors are jumping back in forth between lean and rich.

I took the Pathfinder up some roads around here that have a lot of STEEP hills. I'm very impressed with the new found power and I haven't gotten it over 4500 RPM. With the minimal exhaust I've got (Borla that exits in front of the rear axle) it sounds like it's at about 10,000RPM when the computer says it's at 4000RPM. I have't calibrated the tach yet so it reads high.

I found a couple things....first off, I need another fan. Even with a 17x28x2" Fluidyne radiator it's still getting hot when I start getting on it. On steep full throttle climbs up some good sized hills the water temp would creep to about 190* and drop quickly to 178* after I let off the gas. I'm running a single 16* as a pusher so I'm actually pretty impressed it cools as well as it does.

I've got leaks galore. The entire underside of the engine, steering and transmission are covered in oil. I couldn't even tell if the leak was from the engine or power steering since I haven't noticed a drop in either fluid level. I just ordered a UV leak trace kit last night so hopefully I can fix that soon.

Just wanted to say thanks to everyone on this forum for all of the support. Before this project I had never done anything besides install a bolt on intake or exhaust so putting almost the whole engine together myself and hearing it run perfectly is fairly satisfying. Couldn't have done it without a lot of help from the people on here, though.

On the MAF note, my Pathfinder had an IAT. I wonder what year they started putting those in?

[T45]

190 is the temp at which the stock aux fan in a Q would come on. When it gets over 210-220 that's when it's considered "hot" but I've ran engines to 220-240 and not had any damage and up to 260 while idling...on an iron engine. lol

[tmorgan4]

I thought the fan kicked on lower....I remember reading something Tech said about when the temp starts going over 178* the ECU starts to pull timing.

[T45]

No, I "think" it's 190. It's in the fsm somewhere. I could be wrong though, I got twins...

[Q45tech]

195-200F depending on software version is the start point of timing pull out.

As to MAF it really depends on the need for idle accuracy. By 1500 rpm [where emission test occurs] the MAF is very very accurate.

The Harman Vortex method is very accurate at idle but not so at extreme rpms flows wheras the MAF is extremely accurate. They are opposites in many ways

Depend on what the designers want.

Luckily A/F ratio is not very important as long as you stay richer than 14.7, being lean is much more harmful to longevity than being too rich.

As to idle Nissan just uses a method of idle rpm control and leans the mixture to control rpm [saves gasoline].