Engine doesn't run after plenum pull and few mods! HELP!

[vereshchak]

I pulled the intake manifold for the second time on my 1990 Twin Turbo. The first time was for valve cover gaskets and it went back together no issue and ran beautifully. This time I pulled my plenum to upgrade my fuel injectors to Nismo 615cc and used the early style adapters with new connectors and all new seals. I cleaned and re-sealed my idle air valve because it was leaking boost and put all new silicone hoses. I Installed an AEM Tru Boost Controller and I also installed Z1 Dual MAF but I used an old MAF which i was pretty sure was working fine. I also got a chip tune made by Z1

I went to start my car for the first time after putting it all back together, the engine cranks and fires up but it sounds terrible like i have a few misfires. It will run for literally a couple seconds and then start bogging and misfiring until it stalls out. I tried setting my Selin Translator to ADD instead of AVG (which needs the tune to use both MAF's) and it did help but the problem is still very apparent.

I don't think I messed up the wiring so it makes me think either the injectors are bad, the connectors are reversed polarity, one of my MAF's are dead, or that the chip tune is incorrect

[vereshchak]

UPDATE**

I tried start the car again today and its even worse. When I tried to start it there was no catching of any sort. There was no terrible idle for a few seconds before cutting off. I traced my wires and everything seems to be hooked up correctly. I switched back to single MAF and put my old eprom back in. It tries to turn on a lot more now but still wont fire up. I do smell fuel in my exhaust though.

I guess If nobody wants to help and I dont think of anything else Ill pull my plenum again, put my old fuel injectors back in, put my old injector connectors back in and hope that will work. Ive run out of ideas

[vereshchak]

I also installed an AEM EBC but i doubt that has to do with anything

[nissanfreak12]

Give it some time, some of the guys don't get on here very often.

Have you ohmed the injectors? Are you sure you didn't pinch an oring in the injector?

Pull your plugs and see if they are wet or smell like fuel. Do you have a different ECU to check to make sure the ECU is still working after the tune? Possible the ECU could have been dropped during transit.

Do you have the grounds attached at the rear of the plenum? This one is crucial, if it is not grounded or attached it will cause the PTU to fail

Do you have spark?

[vereshchak]

I have ohmed the injectors and the resistance is nice and low. I carefully aligned all the injector o-ring seals during the install. The grounds are all attached on the plenum and I made more grounding points after doing some research. I havent tested for spark I was just assuming I had spark but I definitely shouldn't be making assumptions. Does Polarity of the injector connectors matter? I feel like if it does that may be my problem. Sorry I just dont usually get stumped over diagnosing so I'm a solid mix of frustrated and anxious, not to mention the car is my daily driver

[ArmedAviator]

Is your tune configured for the increased-flow injectors? If not, it's running far too rich and likely at an A/F ratio making start near impossible.

When changing MAFs and injectors, it's incredibly important for the ECU tune to be tuned for these specific changes.

[nissanfreak12]

Is your tune configured for the increased-flow injectors? If not, it's running far too rich and likely at an A/F ratio making start near impossible.

When changing MAFs and injectors, it's incredibly important for the ECU tune to be tuned for these specific changes.

He did say he had Z1 tune his ECU and with the Selin unit, you do not need a tune for that.

Now that brings up another point from what armedaviator asked, did Z1 tune for a dual MAF setup? if they did and you are using Selin, that could definitely be a problem.

When it comes to the orings, did you use any lube or oil on the orings? did you push them on by hand or use the caps to force them on? Even though they were aligned, its still very easy to pinch those little bastards. If you smell fuel out of the exhaust, its very likely that is what happened. Check your plugs, if you have spark and they are still wet, that could be your issue. If all of them are wet, you might need to look toward the injectors being an issue.

[vereshchak]

I got z1 to make me an Eprom for the 615cc injectors and the dual maf set up. You think pinched o-rings would cause a no-run condition? Id imagine that it would idle poorly due to the s*** fuel pressure but I think it should run? I put them on by hand and carefully inserted the injectors and then inserted the fuel rail to plenum with new o rings too. Should I honestly just pull my plenum again and put in my stock injectors? They ran fine when I pulled them, I already reversed everything else I did.. I dont know what to think!? Do new style injectors ever not work like this? I'm so stumped because I've done the plenum pull before and it fired up perfectly after. I dont think I did anything different this time. I found out polarity of the injector connectors dont matter so I dont think its my new connectors

[vereshchak]

Yesterday I when I put the stock eprom back in with the upgraded injectors it seemed like it had more effort to try and start but still couldnt catch. I dont know if that helps

[vereshchak]

Also ECU diagnostics is flashing code 55 for no malfunctions

[vereshchak]

I completely forgot to mention that when I pulled my plenum I removed my IACV to clean and seal it because I had boost leaks coming from it. I followed this guide http://www.thumper300zx.com/z32/iaa/iaa_unit.htm

I put the gasket on with a bit of gasket maker on both sides too. Hope this helps

[vereshchak]

UPDATE**

I went to check spark out of the two front cylinders (1 & 4) by firing the plug against the manifold, and neither side sparks. I put the plugs back in and cranked the engine over a bunch of times and pulled the plugs again. They smell like fuel and theyre a little damp but I can't say its enough to call the plugs "wet". I checked my coil connectors and every one gets 12.20 volts. So I have no spark and I have no fuel (even though you can kind of smell it in the exhaust after cranking so much). I checked every fuse and every fuse is good.

Another thing I didnt mention is I re wired my Bee-R rev limiter into my ecu. I realized one of my wires was on a wrong wire for a while causing my Bee-R to hesitate. I wired it to the proper terminals at the back of the ecu, but maybe i pulled a wire? Theres no lose wire though so thats probably not the case

[vereshchak]

I checked the connections at the CAS and at the PTU and they seem to be clean

[nissanfreak12]

if the plug is damp at all, it is probably fouled and considered wet. They wont be dripping if that is what you are thinking.

If you can smell fuel, and the plugs are wet, you have fuel. So now you need to figure out why you have no spark. See if you can test the PTU. What series PTU do you have? Silver is 1 and all black is 2. Series 1 is a recall item and mainly found on 1990 Z's

[vereshchak]

I thought I read somewhere it was the other way around? I thought silver was series 2 and black was series 1? I could easily be wrong but mine is all black

[nissanfreak12]

You have the series 2. The silver one is the old style and is prone to failure. The new style is all black. Still try and find how to test the PTU. I know it was posted from a member on this site.

[vereshchak]

I have a spare working PTU on my NA Ill put that in and see if it helps

[vereshchak]

So I went to check spark for cylinder number 2 and it had spark. I tried it again and it had spark again. Tried it a third time and no spark. Used a different coil and no spark. Used a different spark plug and no spark. Used a different coil connector and no spark. Weird...

But the worst thing happened while I was cranking the engine with cylinder 2 open. A piece of one of those blue shop towels flew out of the spark plug chamber. Now I dont know what to think!

[nissanfreak12]

When you had the plenum off, did you plug the lower plenum with shop towels?

[vereshchak]

The lower plenum, the turbo outlets, the intercooler piping. Basically any open hole or pipe. That still doesnt explain where my spark went but I don't know how to deal with this shop towel problem now. Its only a little thicker than paper towel so it cant be that bad?

[ArmedAviator]

The lower plenum, the turbo outlets, the intercooler piping. Basically any open hole or pipe. That still doesnt explain where my spark went but I don't know how to deal with this shop towel problem now. Its only a little thicker than paper towel so it cant be that bad?

They can be quite dense when wadded up and soaked with fuel. It WILL cause issues with valves. Damage them? Maybe if they are held open enough for a piston to slap.

I think it's safe to say that you should stop diagnosing the spark issue at this point, remove the intake plenum/manifold and get any debris/shop towels you can get out of them. Inspect intake ports for remaining towels and carefull remove as necessary - it may involve rotating the crank with a breaker bar to get the valve in an open position to easily extract the towel if it's jammed in there.

[nissanfreak12]

If you restrict the plenum with shop towels you are not getting air to the chamber. This will cause a no start issue. You may not be getting spark at the moment because the spark plugs are fouled. Fouled plugs can sometimes spark and sometimes not.

I agree with AA, you need to take the plenum off and pull out the towels. Also to what AA said, if it does get caught in a valve, it will not seal correctly and not your compression plummets, causing a no start issue or miss issue. As thin as they are they will create havoc in an engine. Especially before the valves because they are soaking up fuel, restrict air, gunking up the valve train. Even if you did get it started and running, you will be very underpowered and not know why.

If you stuffed a towel in the piping to the turbo, and forgot to take it out, you can destroy the turbine housing if it went through it.It may be thin, bunch when its wadded up its almost like having a rock go through the turbine.

[vereshchak]

The only way towels are getting into the turbo is if it exits the exhaust valve. I only had towels in the outlet ports. Damn it this was my biggest fear, leaving a shop towel in there. Im starting to take off my plenum again but how far should I go? Lower plenum? Valve covers? Hopefully not head..

[nissanfreak12]

If you just stuffed them in the lower plenum, you should be able to fish them out that way. You may have to turn the engine if they are stuck in the valves. It could be a very tedious job. Long needle nose pliers, coat hangers, hell even one of those claws that is flexible and small would work. If there are some in the cylinder, do your best with what you have. You could always crank the engine over with a spark plug out, it should pop the little pieces out. Just make sure you pull the fuel pump relay so it doesn't get fuel.

[vereshchak]

So I pulled my plenum in about an hour and a half (fastest yet!) to find cylinders 2-6 each had a shop towels stuck in the valves. I went and bought long needle nose pliers and got my buddy to spin my crank nut until the valves opened one by one to release the towels. Looks like I got everything out successfully but unfortunately I ripped my brand new plenum gasket so I guess I have to wait to put it back together. I guess this is what I get for trying to rush and replace my front and rear steering systems, short shifter, change all my fluids and fuel injectors all in one day, For some reason i saved my plenum for last and started it at after 11pm in my poorly lit garage. Probably the dumbest thing I've done yet

[nissanfreak12]

Don't beat yourself up over it. We all make mistakes, some small some big, thats why everything is a learning experience. Im just glad you were able to find most of it. Are you sure the #1 cylinder doesn't have one lodged deep into it or on the combustion chamber? Just odd you only took one out, but not the others.

I worked in a diesel shop and was rebuilding a 18 wheeler rear end. When I installed the ring I forgot the tighten the bolts on the backside, actually I left about 1/2 of them only snug, but the others were spec'd. Well long story short, 2 weeks later the truck got towed in and missing the 3rd member. Lets just say axles that large are well over 25k.

[vereshchak]

Oh wow that's an expensive hiccup! But that's life, sometimes she goes sometimes she don't.

Im sure that number 1 has nothing. Looking back I remember taking out cylinder 1 but I dont remember removing anymore. It was dark and it was late so I pulled the first one out and my buddy was asking me where I left the ratchet so I went to find it. I guess when I came back since I remember pulling cylinder 1 out I I must have thought they were all out so we slapped on the manifold like a nascar pit crew. Definitely Lesson learned! Hopefully she fires up after this. Do you think I need new plugs? Im going to order them anyway with my plenum gasket

[nissanfreak12]

I would, chances are they are pretty fouled by what you described them.

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Wow guys, I was reading this like it was a Clancy novel. I really hope you resolved this (vereshchak). I'm amazed at the expertize from you guys . Great job nissanfreak12, I sincerely hope you saved the day. Good luck, let us novice mechanics know how you made out.

I've learned so much from you guys on this forum. Thanks !

[vereshchak]

I completely forgot to update this thread! Ive been so busy trying to find a shop that will do an alignment for a very lowered car haha

Anyways I installed my manifold again (this time without the shop towels..) and she fired up! But a heavy misfire. I have on PTU connector that i lost the clip for, had a funny feeling it was that so i taped it together really tight and now we're back on all 6!!

Thanks for the help guys!