'84 boggs some at the top end and 5psi

My car bogs a bit at the top end at around 4-5psi, I suspect O2 sensor, anyone else have other ideas?

I fized the exhaust leak, fixed the boost leak, so neither of those are an issue now.

Mine does it just shy of WOT when rpms are to low for the gear I'm in......like with the rpms around 3000 in 5th gear, and I start making a little boost it will kinda miss a little. Doesn't do this when the rpms are higher, and I'm coming into boost, or at WOT. Don't know what it is....kinda wierd though, although it started when I added the mbc.

Yea sometimes mine seems to back fire when coming boost higher than 5 it doesn't do it often though. What's your AFR doing?

I have no idea, I havent equipped this with a single gauge yet, remember I just got it!

you know I have absolutely no Idea what It could be. My theory? the only thing I could possibly think of in the realm of logical thought is weak coils. I don't think the O2 sensor would cause this. I would think the mixture would be rich if the O2 sensor was bad. How long ago did you get it? (I saw the post and your sig with a new quote BTW)

Aren't you excited about your new car :mrgreen:

My Friends rb20 powered RHD180sx it was detination. It was when we where testing it. No I/C or fan. He was boosting over 20 psi. though.

My Friends rb20 powered RHD180sx it was detination. It was when we where testing it. No I/C or fan. He was boosting over 20 psi. though.

I was thinking maybe he's blowing his spark out... is that max boost for you? 4-5 psi, or is that only moderate throttle? You might be too rich if that is moderate throttle... I have a bad problem with being too rich on my S12... I really need to buy a MAP sensor, and adjust the fuel curve for the car based on MAP, because doing it by RPM doesn't get my anywhere... I also need to rewire my damn TPS so I get a correct reading from it... damn AFC says either 100% throttle, 0% throttle (depending on how I wire it) OR, it will say 100% at idle, and then actually change to 0% at 60% throttle... its weird. But I'm getting 13 volts reading from it... so I need to lower that to 5 volts I think... from what I've read.

If it is your coils, go with some aftermarket coils. Stock OEM ones will run about $150 each at NAPA... MSD Blaster SS coils run $35 each... Just thought I'd throw that out there.

I was thinking maybe he's blowing his spark out... is that max boost for you? 4-5 psi, or is that only moderate throttle? You might be too rich if that is moderate throttle... I have a bad problem with being too rich on my S12... I really need to buy a MAP sensor, and adjust the fuel curve for the car based on MAP, because doing it by RPM doesn't get my anywhere... I also need to rewire my damn TPS so I get a correct reading from it... damn AFC says either 100% throttle, 0% throttle (depending on how I wire it) OR, it will say 100% at idle, and then actually change to 0% at 60% throttle... its weird. But I'm getting 13 volts reading from it... so I need to lower that to 5 volts I think... from what I've read.

tps output is supposed to read 0-5 volts for the safc. you can get a voltage regulator to drop your 12v down to 5 or so fairly easily.

as for your bog, i thought the ecu ignores the o2 at high load...

tps output is supposed to read 0-5 volts for the safc. you can get a voltage regulator to drop your 12v down to 5 or so fairly easily.

as for your bog, i thought the ecu ignores the o2 at high load...

I used an ajustable voltage converter that you plug in to the cigy lighter (you can get them from any car / electrics shop), i removed the plug end and wired it up to a seperate fuse hid it all under the dash, set it to 5 volts and it works perfectly, it was cheep too!

The tps i used was from an s13 (ca18det) i know these run at 5 volts.

I used an ajustable voltage converter that you plug in to the cigy lighter (you can get them from any car / electrics shop), i removed the plug end and wired it up to a seperate fuse hid it all under the dash, set it to 5 volts and it works perfectly, it was cheep too!

The tps i used was from an s13 (ca18det) i know these run at 5 volts.

I've got a TPS off a KA24DE (which I expect is similar, its a 3 wire setup). But the ET original has a different setup, 2 wires... open/closed. So its not wired right. I have it set to be "open" at all times... if not, the car won't run and back fires constantly... =( Its temp fixed at the moment so I can drive it... just one of my many "need to fix" problems... lol. =)

warning: thread hi jacking

my tps is off a ka as well. the ca ecu only uses the big plug (that plugs right into the ka tb connector). make sure you adjust your tps correctly so it reads closed when the throttle is closed. the second plug is where you'll get the throttle % reading for your safc. the ca ecu doesn't need this at all. it's only for safc/datalogging.

you can take the tps off the ka tb and put it onto the ca tb. this gives you a throttle % reading on the stock tb.

How did you "adjust it" to read correctly? I tried a number of times, but can never quite seem to get it right. I mean it seems to work fine at the moment (car drives ok) but what is the exact method of testing it? Which wires am I supposed to be using etc?

Thanks,

get some new plugs, wires, cap , amd rotor more then likely your whole system is too worn out

I pulled the TB and TPS from the '85 Turbo off today and brought it home, as well as I bought a new Bosch O2 sensor, so we'll see.

One step at a time.

Bosch O2 sensor NOOOOOO!!!!!

just ask kieth take it back.

Yeah man........biggest piece of sh*t......although Bart has had good luck with them....so I guess it's hit or miss.
You can get a NTK one by NGK for pretty close to the same price from www.sparkplugs.com and there located down in the LA area so you could probably pick it up and save on shipping prices.

Guys, I'm not driving half way across the State to get an O2 sensor, or waiting in the mail for one.

If I get a bad Bosch, I'll just get it exchanged or go with a uiniversal.

I have to say you should definitely get a ntk, far superior. I've given up on bosch after plug wires and o2 sensors that fell apart. Also if this bog happens under load I dont think it is your 02 sensor because the ecu stops using the signal from it under WOT position and uses a pre-determined set of values to supply fuel. When I first picked up my car all three wires were pulled out of my 02 sensor and it had no power under 3k rpm but once it got there it ram great all the way to redline. Check your coils, cap, rotor and plug wires, they may be the culprits. Oh yeah I've got two stock coils that you can have for free if your are shot, just pay shipping.

Well, O2 is now swapped (how easy it was to do, too), and I removed the cruise control module in the process (since it didn't work anyways). But still no change. Well, no that's not true, it runs better, but the bog is still there.

So new cap, rotor, and Magnecor wires when I get the chance.

You guys don't think it would be the TPS, do you?

Hey I have the same bogging problem. It sounds like the same anyways.... on my car every time i hit the throttle when my boost gauge hits just a tad over 5psi it boggs no matter the rpm? :wtf:. Anyways....i asked a mechanic friend of mine and he thinks its the MAF...could it? aint it rare for one of those to go bad though? I dunno ive had this problem for quite some time now so if you come up with a solution please PLEASE let me know....thx

This might sound weird ...

but, what kind of bog is it?

Does it feel like a fuel cut? (just won't go any faster)

Is it a sputter? (starts missing)

I had a similar problem with mine ... and it was entriely fuel related. Fuel filter helped somewhat, then the fuel pump cacked out.

With the big Carter and new fuel filter, it went away.

Wait ... do you still have your pop-up valve?

The spring can go soft after 20 years, and they start to bleed a bit of boost too early.

This might sound weird ...

but, what kind of bog is it?

Does it feel like a fuel cut? (just won't go any faster)

Is it a sputter? (starts missing)

I had a similar problem with mine ... and it was entriely fuel related. Fuel filter helped somewhat, then the fuel pump cacked out.

With the big Carter and new fuel filter, it went away.

Wait ... do you still have your pop-up valve?

The spring can go soft after 20 years, and they start to bleed a bit of boost too early. This is weird because i have a digi tach and ever since i got the car it always acted up a little.....anyways the weird thing is that my tach stoped working completely at the same time this started to happen???? Also i have took off my pov already and the type of bogg is like....u know how if your on park and you rev a car high until you hit the limit how the car boggs...well my car is doing that only with boost, once i try to go passed 5psi no matter the rpm it starts to bogg(it wont go any faster)...WTF!!!!! PLEASE HELP!!

Matt, it's steady sputter. I suspect both the popup and the fuel pump. I'll start with the popup first, can't we order the right plug fitting from Nissan?

I'll start with the popup first, can't we order the right plug fitting from Nissan?
Just get a 1" threaded pipe plug form any hardware store......it will screw right in. They come in galvinized or brass.

Just get a 1" threaded pipe plug form any hardware store......it will screw right in. They come in galvinized or brass.

then drill a hole in it and tap it for a brass fiting.. its a perfect spot to tab a signal for a boost gauge

then drill a hole in it and tap it for a brass fiting.. its a perfect spot to tab a signal for a boost gauge
That or if you can find one.....the brass plug I got already had a 1/4" threaded hole in it, and I got a 90 degree 1/4" barbed fitting for it.

Lowe's is open late, maybe I'll go later tonight, if I can ever get off my ass and cook dinner first :mrgreen:

Try OSH (Orchard Supply Hardware)....this is where I found my brass plug with the threaded 1/4" hole. Lowes and Home Depot didn't have them when I got mine.......just the galvinized solid plug.

I'll go to OSH today but wait a sec, if Mat's suspicion is right and I have a fuel pressure (pump?) problem, then wouldn't putting a plug in the manifold be a bad idea? It might actually be saving my engine if it's weaker than normal.

No, I don't think a boost leak is the problem.

I'll go to OSH today but wait a sec, if Mat's suspicion is right and I have a fuel pressure (pump?) problem, then wouldn't putting a plug in the manifold be a bad idea? It might actually be saving my engine if it's weaker than normal.

No, I don't think a boost leak is the problem.

Plugging the hole won't cause any change if you are having a fueling issue. Now, if the issue was that your wastegate was stuck closed for some reason (or it wasn't getting a vacuum/boost source) then plugging the hole might cause a problem. If you plug it, just keep an eye on your boost gauge and see if it goes above the normal setting. If it was trying to overboost and the pop off valve was releasing the excess pressure then the car would bog at boost since it would richen too much to burn well. If the fuel pressure is an issue, then the pop off valve won't save anything. It only opens if you exceed the set pressure (which I believe is ~7 psi).

If your tach quits working as the engine is cut, but then comes back on when it is working right, then there is most likely an issue with the Crank Angle Sensor or it's related wiring. You can use one out of another turbo model, or a Z31 if you swap the notched wheel from the S12 into it. Right after I had put my car back together last time I had an issue with the wiring coming from the CAS. There are a bunch of relays at the front of my car that were just dangling free. Once I zip tied them in place where they couldn't move around, it fixed the issue.

If the cut is more of a stutter, then I would suspect ignition components. If it feels more like the engine is just losing all it's power, then it would be more likely a fuel issue. The CAS sensor controlls the ignition and the injectors, so it's a pain to diagnose, but if your RPMs still look right on the dash when you are having your trouble, then it's probably not the CAS.

Sorry to slightly thread jack...

I'm running Copper Denso plugs w/ Advance Auto crap wires... I've got a bad surging/sputter/hard starts (even with my Optima battery, god bless that battery!). I'm looking to get some MSD Blaster SS Coils like Keith, and some NGK 8mm wires, and some NGK Iridium Plugs, but I'm not sure what to buy... Sparkplugs.com lists:

NGK IX iridium 4919 BCPR6EIX-11 0.044 $6.95
NGK IX iridium 3306 BCPR5EIX-11 0.044 $6.95

Which do I want? I'm running 9psi at the moment on my T25, but I'm CRAZY rich, and I'm looking to increase the boost to 12-14psi (I've got 370cc injectors and an Apex'i Super AFC-2). Want to get the best BANG for my buck if you know what I mean...

Thanks,

You'd be fine with the 6EIX which are stock for the intake side and 5EIX for the exhaust side. I don't think you will need to run colder plugs at the boost levels you are running especially if you are running that rich.

Well I know of a good shop that specializes in electrical and tuning, he wont rip me off in price and he knows his stuff, he's a family friend, so let's have him take a look, but I suspect the same... FUEL.

Change the fuel filter, and while you're in there, hook up a fuel pressure gauge and have a look.

Starting to sputter in high boost ... it really sounds like a leak, or faulty ignition. If it was fuel related, it probably wouldn't come back right away.

When my pump started to die, it would be like hitting the rev limiter, just too soon. Then it got progressively worse.

How are your injectors? Take a look at the rubber, make sure there's no signs of leaking.

I know I keep saying "change the fuel filter" I'm not being anal retentive maintenance guy ... these cars are brutally sensitive. I never wanted to believe it, but a lot of running issues went away on my car just by changing the fuel filter and installing a new battery.

Unfortunately with any "new" car, you've got a lot of shit to replace before anything will be diagnosable, just start crossing off some horses before you pay someone to look for Zebras.