HELP PLS!!! Strange thing in VTEC!


Civic Zolee

Civic Zolee

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Joined
Mar 15, 2007
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91
My new B18C build (BC3+cams) was breaked-in (2800km) tuned until 8000rpm! No problem at all! 3 weeks ago I started the engine and I didn't have oil pressure I stopped the engine and brought it to garage. We changed the oil pump and I got back the oil pressure.
I was on my way home when I tried my car against a BMW, then happened a strange thing in VTEC. (The red line is around 8600rpm.) It was around 7500 rpm when it red lined. It is not really like that but very similar. Like ignition problem...

Today we checked: OBD1 conversion harness OK, AFR controlled

We changed also the distributor nothing has changed. We put the vtec shift point to 8500 then no symptoms! We put back vtec to 6000 then again there is problem around 7500 rpm. Tried this several times so I can say this happens only in vtec!!!
Any suggestions? What could have happened? I really don't know what should I check next!
 
*Do you have any error codes identified by check engine light on dash? (Malfunction indication lamp)

*Check yor VTEC solenoid isnt worn-out.... with the engine off unplug the vtec solenoid connector (the grey one. the other [green] is a pressure switch) use a multimeter that can measure resitance in Ohms, check the resistance between a good earthing point (e.g. the earth bolt that goes from cam-cover to front-panel.) And the connector on the actual solenoid so put the pin from the multi-meter into the grey connector, it should be 13-30Ω if its healthy. if it isnt, then double check your ground-test-point (i.e. that bolt) is clean, i.e. going to make a good circuit with multi-meter. clean the bolt with wire brush if you need to.

If is still isnt reading 13-30Ω then you need a new vtec solenoid.

There is a good place to start!

if the resistance is fine then check for continuity (a connection) between the grey connector that would connect to the solenoid (i.e. engine side) AND the pin A15 on the factory OBD2 side of the adaptor harness.

If that come out ok then check for a circuit between WHERE the pin A15 goes to in the conversion-socket against the corresponding pin on the ecu side of the adaptor harness! You might find one of the wires has bad connection on the adaptor harness, good luck anyway.
Hope that helps you out.
 
Thanks for the comment!!! We gonna check the resistence! Other things we have already checked.

Can it be something happened we exhaust system and with higher air flow (vtec) comes this problem?
 
Civic Zolee said:
Thanks for the comment!!! We gonna check the resistence! Other things we have already checked.

Can it be something happened we exhaust system and with higher air flow (vtec) comes this problem?
Click to expand...

I forgot to mention that after several revs in vtec I don't have stable idle. It's wavering. I stop the engine wait 10-15 minutes than I get back the idle.

???
 
So your engine goes into VTEC without any problems, but once it is into VTEC, you have troubles at 7500 rpm. Do I understand that correct ?

So is everything OK then from the start of VTEC (what rpm does it start with your tuned engine?) untill 7500 rpm ?

Because, if so, then your VTEC solenoid will be fine according to me. The only thing the solenoid does is activating the oil pressure for the VTEC cam lobes and maintaining that untill redline at 8000+ rpm.
(VTEC solenoids also hardly ever brake down in my experience).


Seems to me that your engine stops burning fuel at 7500 rpm, and thus make it sound like it goes into redline.

I would say, check your ignition timing and A/F ratio's when you are in VTEC cam lobes.

Also, do you have OEM cam pulley's ? or adjustable ones ?
Maybe check your timing belt too.
Are the alignment marks between crank- and camshaft still OK ?
 
what type of ems are you using? do you have some type or knock control hooked up?
 
switch9 said:
So your engine goes into VTEC without any problems, but once it is into VTEC, you have troubles at 7500 rpm. Do I understand that correct ?

So is everything OK then from the start of VTEC (what rpm does it start with your tuned engine?) untill 7500 rpm ?

Because, if so, then your VTEC solenoid will be fine according to me. The only thing the solenoid does is activating the oil pressure for the VTEC cam lobes and maintaining that untill redline at 8000+ rpm.
(VTEC solenoids also hardly ever brake down in my experience).


Seems to me that your engine stops burning fuel at 7500 rpm, and thus make it sound like it goes into redline.

I would say, check your ignition timing and A/F ratio's when you are in VTEC cam lobes.

Also, do you have OEM cam pulley's ? or adjustable ones ?
Maybe check your timing belt too.
Are the alignment marks between crank- and camshaft still OK ?
Click to expand...

Yes you understand right! :nice: The vtec is at 6000rpm, the ignition timing is ok, AFR monitored in vtec everything is OK! I have BC adjustable cam gears with BC3+ cams.
the cams are not dialed in yet cam gears are at 0,0!
 
Civic Zolee said:
I don't have knock control! I'm using 98 fuel (11,3 CR) would be more than enough!

What does ems mean?!
Click to expand...

ems is engine management system, what are you using to tune fuel and ignition? you also may need to adjust the cam gears... does the care make a pinging sound? what is your ignition set to? if your data loging can you post up a graph with your a/f and ignition?
 
This car is tuned on Crome. AFR is between 12.5-13 on WOT with conservative ignition timing. Dizzy checked, cam timing checked. The motor isn't detonating.
 
itr_henrik said:
This car is tuned on Crome. AFR is between 12.5-13 on WOT with conservative ignition timing. Dizzy checked, cam timing checked. The motor isn't detonating.
Click to expand...

tuned with crome huh? thats too bad, anyways whats the timing set to? whats the timing during the vtec crossover? when you installed them cams did you make sure to install the dowl pin and O ring that go under the center cam cap? i forgot to do that once and i had the EXACT same problem :lol:
 
Today I reved the engine 1st, 2nd, 3rd to 8k rpm and there was no problem!
I can tell that today it's not so cold (+6C) It was much colder when I had the problem. I don't understand!

The dowl pin is installed! I'm quite sure.
 
cold weather should make you run leaner, i wonder if thats a problem? perhaps your gauge is off or the sensor is bad and your running richer than you think, i know when vtec crosses in it dumps alot of fuel in the cylinders it might be bogging...
 
We tried to change spark plugs, wires, distributor no change!

We monitored AFR and it was on WOT from 7.5k to 8.2k 12,5=> 14.2=> 15.6=> 16.1 getting leaner after this symptom! So I think I have problem with fuel supply?!

We tried on half blast to rev until 8k and I had no problem only on WOT!!! :angry2:

I tried today and there was no problem at all! I'm going mad!

We gonna check RC 310cc injectors and fuel pressure...
 
I think I can say that we found the error! Kopp kopp...

AC pump's grounding cable was not tightened enough...

Anyway thanks for all your ideas and comments!!!
 
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