Hesitation in accelleration off idle

[Dattebayo]

My good old trusty (ahem) CA20E almost chokes on it's self off of idle if I give it medium-hard gas. To sum up, car is idling, hit gas medium-hard, engine struggles and tries to die, then stabilizes and revs just fine.

The old plugs seemed to indicate running rich on cylinders 1 and 2, normal on 3 and 4. The engine has a new cap, new rotor and wires, new ignition coils, new plugs. I replaced it all myself, so I know it was done right!
Also, the fuel pump was replaced recently.

Just FYI, this car has an engine management similar to the Z24 engine in the early D21 hardbody trucks. That means 8 spark plugs and 2 ignition coils.

Gimme some ideas, cause it's even more noticeable now that all that ignition stuff has been replaced!

[Dattebayo]

Someone suggested the FPR was not providing enough pressure and this could be why, gonna try the FPR tomorrow.

Gee, this forum is dead dead dead...

[mrzabala]

Just some suggestions but I'm not familar with your fuel managment. But first is there a rough idle issue? Have you had your Fuel mapped and engine tuned? I'd check for a possible vacuum leak, pcv valve, fuel lines and fuel pump (I've seen fuel pumps go crazy and either work and not work randomly and it was due to bad ground and loose wires). Other than that lmk the details, and I'll check it out on my sources. BTW are you the guy that gets anime out with subs and such? If you are- Thank you for all you do.

[Dattebayo]

But first is there a rough idle issue?

No.

Have you had your Fuel mapped and engine tuned?

LOL! This is a totally stock daily driver, not a tuned sport performance vehicle.

I'd check for a possible vacuum leak, pcv valve, fuel lines and fuel pump (I've seen fuel pumps go crazy and either work and not work randomly and it was due to bad ground and loose wires). Other than that lmk the details, and I'll check it out on my sources. BTW are you the guy that gets anime out with subs and such? If you are- Thank you for all you do.

As I said in the first post, the fuel pump has been replaced already with a known working unit, wires were soldered and shrink-wrapped into place to prevent any future problems.

Others have said they thought my issue stemmed from a combination of a bad FPR/fuel rail assembly (it's all one piece in these cars) and possibly a bad idle-up regulator. Vaccuum was applied to the top of the FPR during idle and nothing changed, so I think they might be correct.

Edit: Also, the organization known as "Dattebayo" is formed by many, MANY people, not just one.

[webberpoor]

I've completely rebuilt the engine, installed a new webber 32/36DGEV, spent another $300+ on jet kits, 4 different emulsion tubes and on and on, including several of the best books on Webbers I could find. After 7 months my current conclusion is my problem is much worst with the Webber than the Hitachi. The design of the Z24 intake manifold induces very poor atomization of fuel. When coupled with the Webber relying on vacuum only (the fuel pump only fills the bowl with no pressure to jets) and having an inherent problem with low speed starving (especially on downdraft models) 20+ inches of vacuum can't overcome the volume needed for proper fuel flow thru primary side. With the choke partially closed it runs great, above 3,000 rpm it runs like a Ferrari, but on normal acceleration it pops and gasps.

[Jack S.]

Hesitation (off idle) OBD Code P171

[amc49]

Vacuum leak the most common cause......................

[Jack S.]

I found the air intake cracked or split in the bellows, found a replacement. Hopefully that cleared up the vacuum leak. Check engine light is back on. Still reading code P0171.

[Jack S.]

I've checked for vacuum leaks, replaced the PCV and hose, MAF, Fuel Pump, Fuel Filter, spark plugs, cleaned the throttle plate, and changed the air filter. Clear the code and driving 15-20 miles it throws the P0171 code.

[rabidus]

I've checked for vacuum leaks, replaced the PCV and hose, MAF, Fuel Pump, Fuel Filter, spark plugs, cleaned the throttle plate, and changed the air filter. Clear the code and driving 15-20 miles it throws the P0171 code.

I threw the P0171 code in my 2011 Rogue after putting in a new air filter from Advance auto parts. I didn't know why the code came, I cleaned the Mass air flow and O2 sensor and put in a new Fram air filter from Walmart, cleared the code and the code never came back.

The rubber on the Fram air filter is thicker than the one from Advance auto parts and fit in the air box a lot tighter.