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Mobious5

shaved intake 280zx, now won't start

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Mobius5,

Here is an intake swap with a 60mm TB conversion I just completed yesterday for a local customer. Some of the details may be of help in your project. Local customer located a non-EGR N-42 intake, 60mm TB, Pallnet fuel rail and TB spacer kit then dropped the car off and wanted it installed and tidied up similar to what we have done for many others, including rerouting the EFI harness along the firewall and under the fuel rail instead of over the middle of the plenum. Fired the car up yesterday, runs great, just as it did when it came in, other than the deleted air flow regulator as described below, other than that, no differnet! :2thumbs:

 

This is a bone stock L-28 EFI.

 

Items deleted;

1) EGR, (This is a ’75 car registered outside of CA)

2) Air Flow Regulator (for a cold idle speed that the engine will idle on its own without holding the gas pedal, a "warm" idle speed has to be approx 1000-1200 RPM on a properly tuned L-28. If a warm idle speed of 650-800 is desired, then you’ll have to hold the gas pedal to keep the car running when cold till the car warms up, or reinstall the Air Flow Regulator.)

3) Coolant by pass that ran under the Air Flow Regulator.

4) Cold start injector and Thermo time switch. Tapped the cold start injector hole for 1/8" NPT, brass pipe plug installed. (left the Thermo-time switch in the thermostat housing, just deleted the wiring.)

5) A/C equipment in the engine bay.

 

Items rearranged; but still functioning as OE!

1) Carbon Canister vacuum line has new port drilled and tapped into the back of the plenum and vacuum line rerouted along passenger frame rail and across the lower firewall.

2) Fuel Pressure regulator relocated to the firewall, fuel rail plumbed in a pseudo dead head style arrangement, (before anyone jumps on the “dead end EFI fuel systems cant be done†bandwagon, SEARCH! It can, has, and is still being successfully done, by the OE and tuners such as myself with NO ill effects NO vapor lock etc). Vacuum port of the FPR also has its own new dedicated vacuum port added to the back of the plenum next to the canister port.

3) PCV is now drawing fresh air, K&N filter on valve cover. (This caused the engine to ingest "false air" as the air being drawn in through the PCV system is no longer being measured by the AFM, yet the engine is breathing that air, i.e. “false airâ€), as such I will be fine tuning the part throttle tune with a combination of the water temp resistance and AFM adjustments, todays project. For those new to the stock EFI or EFI in general, just leave the valve cover breather plumbed to any port between the Throttle body-butterfly and the AFM and you’ll be just fine!

4) Removed the EFI harness and removed the outer sheathing from the harness that resides in the engine bay. Deleted the Thermo-time switching wiring back to the splice, also deleted the cold start injector wiring. (Just leave the wires cut, but protected from grounding/shorting. The computer doesn’t know the difference nor does the engine.) Separated the injector wires and the water temp sensor wires of the AFM and TPS wires into two separate runs. Retaped those as 2 runs. Reinstalled harness, routed the injector and water temp wires along firewall and then under the fuel rail, (can’t even really see them in this photo below, but they are there) and routed the AFM and TPS wires back in the stock location.

 

Customer wasn’t ready to for a shaved intake, so this one was just painted and installed. Original fuel pressure regulator port plugged as well as a couple other deleted vacuum ports.

 

Here is the picture, below that is a diagram of the dead-head fuel rail system.

 

Boot between TB and AFM is not secured in picture, it needs to be secured!

 

 

 

 

 

 

Hope this helps,

Paul

 

 

Wow! Awesome post. Inspired me to start cleaning up my intake. Now I need to install my new JSK fuel rail, new injector clips, and re-route the wireing.

 

So if I want to install a valve cover filter, it would best to wait till I get Megasquirt??

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i finally got the car running ok... i adjusted the idle screw on the TB and i hooked that pipe under it to my PVC valve then to a vacume line to the pump. i didnt screw the PVC onto the intake i just leave it sitting there.

 

i have the to hoses leaving the charcol canister unpluged. (i dont no if thats good or not)

 

i have another problem though, at first the car wouldnt come out of first gear (automatic trans) till 45mhp and 4k rpm. i was like wtf.. then i noticed a tear in the vacume line from the intake manifold to the trans line. i replaced it just now and is all better.

 

but where the problem lies is, the car dosent have the same get up and go as it used to. i cant squeel tires and now my o-60 is like 20sec. a 50 ton 18 wheeler would destroy me off the line.

 

do you have any clue what could be going on? i checked vacume... could it be the timing? i dont no

 

i hope its the timing because the car sounds like its caming. i can hear the rockers clicking pretty loudly. the vacuum advance is still hooked up..

 

help...

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but where the problem lies is, the car dosent have the same get up and go as it used to. i cant squeel tires and now my o-60 is like 20sec. a 50 ton 18 wheeler would destroy me off the line.

 

 

Thats funny!:)

 

Good job on the progress, personally I don't have any advice at this moment.

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i finally got the car running ok... i adjusted the idle screw on the TB and i hooked that pipe under it to my PVC valve then to a vacume line to the pump. i didnt screw the PVC onto the intake i just leave it sitting there.

 

i have the to hoses leaving the charcol canister unpluged. (i dont no if thats good or not)

 

i have another problem though, at first the car wouldnt come out of first gear (automatic trans) till 45mhp and 4k rpm. i was like wtf.. then i noticed a tear in the vacume line from the intake manifold to the trans line. i replaced it just now and is all better.

 

but where the problem lies is, the car dosent have the same get up and go as it used to. i cant squeel tires and now my o-60 is like 20sec. a 50 ton 18 wheeler would destroy me off the line.

 

do you have any clue what could be going on? i checked vacume... could it be the timing? i dont no

 

i hope its the timing because the car sounds like its caming. i can hear the rockers clicking pretty loudly. the vacuum advance is still hooked up..

 

help...

 

You're using PVC on your Z car?? haha

 

PCV = Positive Crankcase Ventilation.

 

The car sounds like it's camming? What does that mean?

 

Revv the motor up manually to about half throttle, and then play with the AFM under its plastic cover. If it runs better when you pull the weight counterclockwise its running too lean, and too rich if it runs better the other way.

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You're using PVC on your Z car?? haha

 

PCV = Positive Crankcase Ventilation.

 

The car sounds like it's camming? What does that mean?

 

Revv the motor up manually to about half throttle, and then play with the AFM under its plastic cover. If it runs better when you pull the weight counterclockwise its running too lean, and too rich if it runs better the other way.

 

haha oops.

 

yes sir, i have it between the bottom pipe under the TB and a vacuum line...

 

i'll try that this afternoon!

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haha oops.

 

yes sir, i have it between the bottom pipe under the TB and a vacuum line...

 

i'll try that this afternoon!

 

Good luck! Do you have any spare AFMs? I have about 3 or 4 so I actually adjust the spring rate on mine to get the AFR in range. It's usually frowned upon but I have several so if I mess one up it's not a problem.

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i think i may have found my problem causeing my power lag and loss of acceleration. im missing furthest left and furthest right exhaust/intake gasket.... sooo theres black carbon and exhaust leaking everywhere.

 

i got a new gasket and two bolts so im hoping this will fix my problem!!!!

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My 2 Cents

 

Deffinately sounds to me like your piping isn't ran right all the way and u deffinately still have a vacuum leak

 

I do remember another thread that was discussed stating if your not going to hook up both pcv hoses to the intake, the one ontop the valve cover and from the block you should put a filter on them because it will cause a another vac leak. As for the idle screw, I don't beleive it will work properly with out the iac tubing (mess) is hooked up.

Edited by texanredneck
Rememberd other thread

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i think i may have found my problem causeing my power lag and loss of acceleration. im missing furthest left and furthest right exhaust/intake gasket.... sooo theres black carbon and exhaust leaking everywhere.

 

i got a new gasket and two bolts so im hoping this will fix my problem!!!!

 

I left two injector o-rings off when I shaved my manifold and my car ran like crap :facepalm:

 

Just remembered that, if that doesn't fix the problem you should go back and make sure one or two didn't fall out.

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word to he wise :) from experience start from the easy things and cheap things to fix thing first. i learned the hard way on my zxT project i just started. i even have a thread about it asking for help. except mine wouldn't start PERIOD. :P (turned out i had 4 bad injectors)

 

start off by making sure theres even GAS going into the injectors(maybe ur only running a few)

move into checking if gas even comes OUT of the injectors.

then spark

then timing. then vacuum leaks. since lines are difficult to get right without a 280zx haynes :P

 

if all else fails buy it off ebay :)

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Well I just finished shaving my intake and adding a custom fuel rail. Its an 83 ZX and for some reason I cannot get it to rev? It will idle, low.. but it will idle. But once I barely touch the throttle it boggs out. I cannot for the life of me find a vac leak. Everything is grounded.... And I am just completely stumped. I also followed Braaps little write up for shaving the intake. At a total loss, for some reason everyone else has the complete opposite?

 

 

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3) PCV is now drawing fresh air, K&N filter on valve cover. (This caused the engine to ingest "false air" as the air being drawn in through the PCV system is no longer being measured by the AFM, yet the engine is breathing that air, i.e. “false airâ€), as such I will be fine tuning the part throttle tune with a combination of the water temp resistance and AFM adjustments, todays project. For those new to the stock EFI or EFI in general, just leave the valve cover breather plumbed to any port between the Throttle body-butterfly and the AFM and you’ll be just fine!

 

Old thread yes.  Paul is there a reason the Valve Cover Breather has to be tied there?  Can it be tied back into the PCV valve underneath the intake like the block? I was wanting to eliminate it from the TB.

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Not Paul, but on EFI if you are using an AFM ( flappy doodle ) or MAF ( Mass Air Flow ), ALL of the air that is ingested by the engine has to be maesured by the AFM or MAF.

 

The PCV system is a loop system. Fresh air is drawn through the Valve Cover ( and naturally needs to have some form of Air Filter ) into the crankcase ( big freaking hole though timing cover to oil pan ) and then extracted through a breather port in the block and then finally drawn into the inlet manifold through the PCV valve. The PCV Valve is nothing but a metering valve. Now the crankcase fumes ( mainly ring blow-by ) are somewhat combustible and the outside air flowing through the system has to be accounted for by the ECU on a AFM or MAF EFI system. Otherwise the  will be thrown out of whack. Early L-Jetronic  EFI systems have no feed back loop ( O2 sensor ) to self correct the mixture. So you must make sure that the PCV system is properly routed and the Intake air is drawn through the AFM.

 

One exception is if you are using a Speed Density EFI system. Speed density does not use any type of Air Flow measurement device.  Only a MAP or Manifold Absolute Pressure  sensor . Then you can use a K&N style filter on the Valce Cover vent. There is no advantage to doing that, other than esthetics.

 

The other exception is carburation. Carburated cars are already calibrated for the bypassed air used by the PCV. The vent line goes from the valve cover to the inside lid of the air cleaner to draw in fresh air. You can use a K&N style filter on the Valve Cover of carbed cars as well. It will make no difference to the closed loop function of the PCV system nor the fueling calibration.

 

Hope this helps. And BTW... you ALWAYS want to run a PCV system on a Daily Driver. The Positive Crankcase Ventilation systems main job is to remove contaminants and acids in the engine oil caused by ring blow by. Secondary action is that it provides a negative crankcase pressure under most operating conditions that improves Piston ring seals and also reduces oil leaks from crank shaft seals and engine gaskets. The seal lips are designed to operate normally with a Negative crankcase pressure, not a positive crankcase pressure.

 

Race cars can get away with Vent To Atmosphere oil breathers and catch tanks. They change oil often ( gets rid of contaminated oil ) and run Dry Sumps or Vacuum pumps that create negative crankcase pressure ( for improved piston ring seal )  But VTA is not a good idea on a street car, IMHO.

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Thanks. Totally forgot about the timing chain hole. Why is the crankcase vented to the PCV with no vacuum at WOT but the valve cover is run to the intake hose after the AFM but before the TB? At WOT, why wouldnt both be Plummed between TB and AFM? Or even at idle for that matter.

At WOT there is no vacuum and the PCV is closed. So the closed loop is drawn back through the valve cover but is not metered because it's after the AFM? Or because it is after the AFM it's already been read?

 

EDIT: I got it I read the FSM! Go figure.  It does reverse at WOT.  Thanks Chickenman.

Edited by JSM

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Not Paul, but on EFI if you are using an AFM ( flappy doodle ) or MAF ( Mass Air Flow ), ALL of the air that is ingested by the engine has to be maesured by the AFM or MAF.

I am curious though, from a pure air to gas ratio burning in the cylinders, how does the air entering into the block have anything to do with the calculation needed by the EFI for normal operation? Is the amount of air (pressure from combustion) somehow entering the combustion chambers and the ECU has to compensate for this during the normal cycle of the engine?

 

I know from Paul's post on page one he had to adjust for this because he vented the valve cover so it has to, But if both the block and valve cover were vented outside of entering the intake, an adjustment to the EFI would still be needed?

Edited by JSM

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Fuel charge is calculated based on the amount of air going into the cylinder. If the air is not all drawn through the metering device, then the mixture will be calculated based on incorrect information and will be lean due to the additional air.

 

The air entering the block through the valve cover matters because that air is eventually drawn into the intake through the pcv valve on the bottom of the intake.

Edited by ZHoob2004

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So with that logic removing both PCV and valve cover inlet from the EFI intake would eliminate any AF ratio issues from normal combustion?

 

Yes, but you don't want to ever do that ( remove PCV system and replace with VTA )  on Daily Driver car. You will get much quicker contamination of the oil. Carbon particle contamination, water vapor and acid buildup. As wee the piston ring seal will be affected, negative crankcase pressure aids ring seal. The crank seal and rear main  seal will all be less  effective as the sealing lips are designed to operate at negative crankcase pressures. Note: the odd WOT pass is usally only for a short time, and any pressure buildup in the crankcase will be relived once the throttle is lifted.

 

Oil contamination is the main effect though. Carbon particles and acid buildup are nasty. Rod and main bearing life will be shortened.

 

The following article explains the benefits of a Positive Crankcase system:

 

http://www.agcoauto.com/content/news/p2_articleid/197 

 

 

In addition; 

 

Quote from Engine Labs article

 

PCV and It’s Importance

All internal combustion engines generate some type of crankcase pressure in the form of blow-by. Blow-by is combustion gasses that escape past the piston rings. In the early 1960s, General Motors identified crankcase gasses as a source of hydrocarbon emissions. They developed the PCV valve in an effort to help curb these emissions. This was the first real emissions control device placed on a vehicle. While most of us who are performance enthusiasts will roll our eyes when emissions controls are even mentioned, GM actually did the performance world a favor here. Not only does a properly operating PCV system reduce the overall emissions output of a vehicle while at the same time not sacrificing horsepower, it also has other benefits. It improves gasket seal, and prolongs gasket life by reducing the blow-by effect. Further, it also helps reduce the amount of oil an engine consumes through the combustion cycle, or loses due to leaking seals. 

 

 

 

 

With race cars it is not such a big issue ( using Vent to Atmosphere of Cranccase and Valve cover ):

 

1: Race cars change oil frequently. Usually after one race. 

 

2: Real race cars have Dry sumps or Vacuum pumps for the sump. The scavenge stage in a Dry Sump creates a strong negative pressure in the sump. This helps with ring seal immensely. Some NASCAR engines are pulling well over 14 inches of vacuum in the sump. HP gains  of 20 to 23 HP on a 600 HP engine with 12 to 14 inches of vacuum are common. Better ring seal, enabling the use of low tension rings  and reduced windage in the sump are the reasons for the HP gain. 

 

The following article explains the importance of maintaining a negative pressure in the cranckcase.

 

http://www.enginelabs.com/engine-tech/engine/tech-crankcase-pressure-control-oil-and-air-control/

 

Edited by Chickenman

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From engine labs article:

 

Ring Seal and Pistons

Ring seal plays a vital part in how your engine uses oil and performs as well. Proper ring seal reduces blow-by, thus decreasing pressure inside the crankcase. Running a vacuum pump in a racing engine, you can actually change to a lower tension ring package, using back cut rings instead of the older style high-tension D-rings. This allows for lower internal friction and an improvement in overall engine performance. 

We talked with Gary Meier of JE Pistons about this. Meier tells us “Ideally you want a back cut ring with gas port pistons, the system seals better and is more efficient. If you run with a D-wall ring you are only going to gain a minimum amount of power.”

Meier points out that using gas ported pistons with lateral ports is the best choice. “In the old days, guys would argue that the gas ports would get clogged up and then they weren’t doing any good. These days the fuel is so much better that it has eliminated that argument unless you are running extremely rich or something else is wrong,” says Meier.

je-piston.jpeg

Since running a vacuum pump pulls oil away from rotating components and back to the pan, windage is reduced. The more is better approach does not apply to engine vacuum however. Running a high level of vacuum can have an adverse effect on engine life.

While Meier was able to tell us “On a standard 600 hp engine, 22-23 hp is not out of the question with vacuum at around 14-15 inches of mercury.” While some high-end race cars will push beyond those numbers to run over twenty inches of vacuum, these are cars that are generally towed and pushed through the staging lanes and their engines live the majority of their lives either warming up for a race or making a pass at the track. 

 

“Above 14-15 inches of vacuum, you pull too much oil away from the wristpins and cylinder walls,” said Meier. In these cases, the higher end engines will employ measures such as oil squirters to spray the wrist pins, as well as special camshaft squirters, and even other provisions to oil the rocker arms and valvetrain. All of this must be taken into account when running higher levels of vacuum. 

main_ringsets.jpgWhile vacuum pumps in the past have been thought of as something for high-end dry sump race engines only, they can also increase the power in a wet sump system as well. Meier recommended this for drag race engines only however. He also stated that the horsepower gains would not be nearly as significant as it would be with a dry sump system. In wet sump systems the expected horsepower gains would be in the neighborhood of 6-12 horsepower.

The same rules apply with regard to running too much vacuum. Peterson Fluid System’s, Wade Moon, pointed out that his company offers a single-stage wet sump external pump with a section on it just for pulling vacuum. 

Edited by Chickenman

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Yes, but you don't want to ever do that ( remove PCV system and replace with VTA )  on Daily Driver car. You will get much quicker contamination of the oil. Carbon particle contamination, water vapor and acid buildup. As wee the piston ring seal will be affected, negative crankcase pressure aids ring seal. The crank seal and rear main  seal will all be less  effective as the sealing lips are designed to operate at negative crankcase pressures. Note: the odd WOT pass is usally only for a short time, and any pressure buildup in the crankcase will be relived once the throttle is lifted.

 

Understood.  My thought was to run the PCV, before the AFM so it could be metered and vent the valve cover , but with the oil vapor aspect of it it probably wouldn't be good for the AFM!

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