b18c1 block, b16a2 head. obd2a.

Once the car reaches operating temperature and has been driven for approx 10-15 minutes, the motor will start to bog out at anything under ~3500rpms upon acceleration.

The timing was checked and the issue came up at both 16 and 18 BTDC. The belt is brand new and was installed correctly. We acquired those reading with a dial-in gun for maximum accuracy.

When we checked for spark issues, we found some oil in the valve cover where #1 goes. So today we removed the cover, applied a new gasket set, and sealed accordingly. No more oil flow there... but still the same problem.

The O2 Primary sensor was just replaced as well. There are no CELs whatsoever being thrown.

The fuel pump is a Walbro going to a stock regulator. Is it possible that the Walbro put out too much lph for the stock regulator to handle? This and fuel filter itself seem to be the only ideas we have left.

Any suggestions would be appreciated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrAngry &raquo;</TD></TR><TR><TD CLASS="quote">b18c1 block, b16a2 head. obd2a.

Once the car reaches operating temperature and has been driven for approx 10-15 minutes, the motor will start to bog out at anything under ~3500rpms upon acceleration.

The timing was checked and the issue came up at both 16 and 18 BTDC. The belt is brand new and was installed correctly. We acquired those reading with a dial-in gun for maximum accuracy.

When we checked for spark issues, we found some oil in the valve cover where #1 goes. So today we removed the cover, applied a new gasket set, and sealed accordingly. No more oil flow there... but still the same problem.

The O2 Primary sensor was just replaced as well. There are no CELs whatsoever being thrown.

The fuel pump is a Walbro going to a stock regulator. Is it possible that the Walbro put out too much lph for the stock regulator to handle? This and fuel filter itself seem to be the only ideas we have left.

Any suggestions would be appreciated.</TD></TR></TABLE>


getting any smoke?

 

No smoke at all. Basically no indicators of easy-to-spot problems besides the bogging and rough idle at startup if started within an hour of another bog session.

Oh, and when it is bogging, it will also idle very low when it's not in gear. Around 250 or so - near stall level.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrAngry &raquo;</TD></TR><TR><TD CLASS="quote">No smoke at all. Basically no indicators of easy-to-spot problems besides the bogging and rough idle at startup if started within a few hours of another bog session.</TD></TR></TABLE>


hows the condition of the cat? what ECU are you running?

 

The cat is brand new as well. ECU being run is an OBD2A P72.

Could crank sensor wiring have anything to do with this? We used an OBD2B harness between the OBD2A engine side and OBD2A chassis side and had a crank sensor CEL a week or so ago.

After acquiring the proper diagrams, we got the sensor to go away after wiring the correct pins..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrAngry &raquo;</TD></TR><TR><TD CLASS="quote">The cat is brand new as well. ECU being run is an OBD2A P72.

Could crank sensor wiring have anything to do with this? We used an OBD2B harness between the OBD2A engine side and OBD2A chassis side and had a crank sensor CEL a week or so ago.

After acquiring the proper diagrams, we got the sensor to go away after wiring the correct pins..</TD></TR></TABLE>


its possible but one thing that could be causing your bog is the fact that the p72 is looking for the secondaries and is not finding them, thus richening up the mixture, etc etc etc

 

What kind of spark plugs are you running? Spark plug wires? I've seen bad spark plugs (even though they were new) do this. Bosch platinums and split fires are notorious for causing bogging at the 3-4k rpm level. I'd try 'em with a stock set of wires too, just in case.

ThiNGK fast

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by temp &raquo;</TD></TR><TR><TD CLASS="quote">


its possible but one thing that could be causing your bog is the fact that the p72 is looking for the secondaries and is not finding them, thus richening up the mixture, etc etc etc</TD></TR></TABLE>

Nah, I ran a P72 w/o butterflies. Aside from the VTEC coming on way too early, it was fine.... and the computer doesn't try to activate the butterflies until 5700-ish, and would rely on sensor data to enrichen as necessary.

 

That would make a lot of sense..

However, the car didn't have this problem when the crank sensor was left disconnected. Could an ECU reset possibly allow for it to learn to draw from only the primaries or is my only option converting to OBD1 ?

We tested the plugs and wires, all performed fine. The engine dipped down accordingly whenever they were removed. The wires are stock. I do have some spare plugs from my old GSR, I'll give it a shot..

 

That's odd that you say that about VTEC coming in early.. mine doesn't kick in until around 4650 or so.. kind of late if anything.

 

^^^

 

on the plugs: from my experience, the wrong set of plugs will allow the car to run normally, but right at that 3500 range, they'll collectively start firing wrong or something. I know it sounds weird but everytime we saw this at the shop where I used to work, the first thing we would do is put a set of OEM NGK's in and 99% of the time, that would fix the problem, no bull ****. Definitely try this!

As for the VTEC engagement point: I was running B1C1 block, stock P72 cams with an ITR manifold on a PR3-1 (B17A, but identicle ot B16) head. What I had (and you too, essentually) is a version of the 'poor man's type R. B/c of the larger, shorter intake manifold runners, a later VTEC engagement is better, probably about where the ITR VTEC engages (5700-ish). Remeber, on a completely stock B18C1, you have VTEC at 4500 (@WOT), but you're still on the first intake manifold profile (smaller dia. runners). The smaller runners help sustain the air velocity needed to make power at lower RPMs. But on your set up, when the VTEC hits, you already have the larger intake manifold so you loose some of the velocity from the intake manifold. If you go to dyno it you'll notice the graph dips at the VTEC point, indicating that it should occur later in the RPM band.

 

i'll try the plugs.

the problem is happening at anything BELOW 3500 though. VTEC works like a dream as does the range from 3500 and above..

 

id probably be leaning towards this... just because the b16 doesnt have secondaries... on a p72...youre running on only 4 runners up until...3500-5600. depending. after that...another four runners=8 runners are open!

 

you know if your running too lean?

 

don't appear to be, plugs look fine. the ecu would throw a code if i was in either case.. i might just upgrade the FPR for the sake of having an adjustable one w/ meter..

 

^^^^^

 

would a faulty sensor (one that doesn't throw a code) do something like this?

 

if you know of any sensors that i don't, please drop some knowledge.

 

By any chance would you happen to have a VAFCII installed?

I had a similar problem to yours, and I went through hell and back before I finally figured out it was nothing more than a shitty wiring job done by the previouse owner who installed it. Even if you don't have a VAFCII installed you might wanna check the wiring on your ecu & harness.

Just try the simple solutions first. thats my 2 cents.

 

no v-afc installed.

id like to check the wiring too.. however, once again, i only have one clue as to what might be causing it.. but nobody has confirmed if the CKP sensor could be doing this..

 

BAWMP!

 

afternoon molliwhomp.

 

after lunch!

 

bizzumpz.