GBL1

Here's that facts...I tried to keep it simple...looking for ideas of what's wrong. I bet it's something simple, stupid, and easy to fix, but....


2000 Honda Prelude, base model w/ 5 spd manual – 121K miles

Recent tune-up (plugs, rotor, cap, wires, & fuel filter) replaced at 114K miles, v-tec solenoid cleaned out & new rubber gasket installed at 120K miles. Has slight oil leak & power steering leak to be addressed, as I’m able to do so.

Car ran perfect…passed state emissions test on Aug 3rd. Previously threw check engine light code for O2 sensor # 1…only when driving through heavy rain (wet connection?). Reset CEL after rain = no problems afterwards.

Took it in to a shop for timing belt service (I KNOW…recommended at 105K miles) & to have a performance header & catback exhaust installed…kept stock cat in place.

Got car back: ran funny & would not kick into v-tec at 5200 rpm…also had an exhaust leak at header/mid-pipe flange.

Had a Honda dealer tech drive car: he said it ‘may’ be ‘off’ by one timing belt tooth…to the exhaust side if it is.

Returned car to installation shop: they checked it over, said timing was dead spot on, but that two connectors underneath that control timing were plugged in, but not ‘snapped’ fully. Assumed it was just a loose connection. Car runs great now…except for exhaust leak and periodic check engine light coming on (assumed to be O2 sensor # 1).

Removed mid-pipe & determined that one stud was cross-threaded preventing a full, tight seal. Forced to drive car w/ open header for 2 miles during course of the repair…but did not “get on it” at all. Replaced stud & gasket…no more exhaust leak. Added an O2 ‘simulator’ (metal extender sleeve in between sensor & exhaust pipe) thinking that sensor was getting too much from now bigger header pipes.

Car runs & sounds GREAT now (nice deep tone hum to the exhaust) except for “occasional” (about 10% of the time) v-tec not kicking in…car just stutters & sputters at v-tec rev mark (5200 rpms). CEL now coming on regularly after 10-15 minutes of driving. Had code pulled…indicated “O2 sensor # 1: low voltage”. Likely needs to be by-passed or replaced now…

Drive car one mile away after getting code pulled: now stutters & sputters at various rpms…and dies. Car turns over but will not start….as if it’s out of gas, but it has half a tank full.

Waited approx. an hour: car started right up & revved fine. Ran for maybe 15 seconds, then died again…& will not restart. Waited a few more hours, tried again, got same results…car started right up & revved fine. Ran for maybe 5-10 seconds, then died again…& will not restart.

Pulled plugs: appear normal, no indication of fouling. Checked all connections, everything looks fine.

I, an auto mechanic student friend at UTI, his buddy…a mechanic, a current high school auto shop teacher (former tech at a car dealership), and various other auto-mechanically knowledgeable friends are all TOTALLY STUMPED…

ANY ideas from the audience???

Rosko

iTrader: (1)

All the stuttering and sputtering to me points back to those sensors that were only partially connected. Those are what control your ignition timing, I would look those over and make sure they arent damaged or look like they were damaged at one point and repaired. Those wires are very sensative, they are signal wires so if they were cut at one point and not repaired correctly the signal from one wire could be transferring to the other and confusing the ecu. (I'm not talking about wires directly touching either), its more of a emi issue. May not be the problem at all but I know those wires are picky as **** and it sounds like there was an issue with those plugs already...

typemismatch

Try putting your cat back in temporarily, I had an EP3 I used an o2 simulator on with a DCRH that didn't work too good, and even backing the sensor out of stream didn't solve it completely. When I would get the CEL it would run rough and dump fuel.

Mind you, my EP still started and idled ok, but you sound like you have done a few things relatively close together, try isolating your problem to just one change.

snobordboy

Why not replace the front O2, do a reset, and see what happens once you have that solved? The rear one is just there to tell the ECU that the cat is functioning properly, while the front actually helps the ECU adjust open loop fuel trim.

andoxviii

iTrader: (1)

http://autorepair.about.com/od/engin..._hot_start.htm

If that doesn't help, get another shop to check the timing. It certainly sounds like the timing is off by a tooth or two.

bluedlude

you have an O2 sim on your primary sensor?

GBL1

I plan on switching it out, but the O2 sensor alone would not cause the car to not start...I need to focus my time, energy, & $$$ on the bigger problem first.

I'm betting it'll be a fuel issue of some sort...

GBL1

Yes, why?

B serious

iTrader: (1)

Who suggested that you sim the PRIMARY O2 sensor? Bad idea. You don't sim that one. The primary O2 sensor is not just a monitor like the secondary O2 sensor. It's a fuel control. It feeds information back to the ECU to let it know how much fuel to add/remove under closed loop cruise conditions or slight acceleration conditions.

Never never never use an O2 sim for the primary O2 sensor. You want actual information about fuel trim going back to the ECU...not sim'd information.

The stuttering and not going into VTEC is most likely another issue since the primary O2 sensor is ignored by the ECU during heavy acceleration. During heavy accelration, the ECU goes back into open loop. I think that the threshold is like 25% throttle angle...but don't quote me on that.

I had a similar problem with a 5th gen. The car would sputter and wheeze under heavy acceleration and would NOT go beyond around 5500RPM if I applied more than about 50% throttle angle. It would, however, rev to redline reluctantly if I applied light throttle.

It turned out to be a clogged cat in my case.


-First, take that sim off the primary O2 sensor. It can't be there.
-Then, remove the cat completely. Let the secondary O2 sensor dangle there or just zip tie it to something.
-Drive the car open header and see if it revs out normally. You can get on it. Don't be scared.

To diagnose the one I fixed, I just removed the cat and looked inside it. The substrate was broken and clogging the passage. I was clued into this because of all the rattling coming from the exhaust. I then drove it around for about 10-15 mins open header and got on it pretty much 100% of the time. The car ran beautifully. I smashed out the substrate using a pipe. Then bolted the hollowed out cat back on and used an O2 sim on the REAR O2 sensor.

It was a friend's car. He got a replacement cat later...but my home made test pipe worked perfectly for the mean time.

bluedlude

it is a fuel issue. the moment your car starts its looking for info from that primary sensor telling it how much fuel to give. its probably DUMPING fuel in to compensate. replace that sensor man

B serious

iTrader: (1)

No. When the car is started cold, it is in open loop. The primary O2 sensor might as well be on the moon at that point. It doesn't matter.

Even when the car is started warm, it is initially in open loop. The car is also in open loop under moderate or heavy acceration. Open loop means that the information from the primary O2 sensor is ignored. The ECU adds/subtracts fuel based on a speed/density formula. Meaning it gets all it's info from the MAP, TPS, and IAT.

So a stutter under heavy acceleration and the car not going past 5500RPM is *probably* not due to the O2 sensor. There may be some crazy ECU design parameter that preludes have that NO other hondas have...but it's highly unlikely.

I think people are confused about the role of the primary O2 sensor. Basically speaking, the primary O2 just wants to make the ECU run the engine at 14.7:1 air:fuel ratio. It's allowed to do that during either light throttle cruise or idle. It does this by reading the exhaust stream. A rich exhaust stream (lack of oxygen) means that the O2 sensor voltage goes up. A high voltage signal to the ECU tells it that it must lean out the air/fuel. The opposite happens when the O2 sensor sees a lot of oxygen in the exhaust (lean mix). It will send a low voltage signal to the ECU and the ECU will richen up the mix.

HOWEVER, the ECU will modify fuel trim as it sees necessary. It will ignore the O2 sensor when it needs to. If you add a load to the engine or if you accelrate harder, or whatever. The ECU will run the car in whatever trim it sees as "optimal".

That's a very simple and easy way to explain the job of the primary O2 sensor. So no...it WILL NOT affect VTEC operation. WILL NOT affect full throttle operation.

DJ_SaNdOz

Have you rechecked the new fuel filter? It could potentially be clogged. Sounds like a fuel problem to me.

A Blue Lude

Fix the O2 sensor first. It is a major piece of the EFI puzzle, something you will need to fix anyway, and a plausible enough issue. While the ECU will ignore the O2 sensor if it gives totally spurious readings, I am not sure what the spacer will do.

Although they are not massively important (and are cleared by ECU reset), trims set by closed loop operation do affect open loop fueling. And your closed loop operation could be pretty fubar at this point.

Also, what Rosko says is important - those crank sensors that were not plugged are very important and you'll have big issues if they are wrong in any way.

gstrudler

As mentioned several times, I would replace the primary o2 since it needs to be done. You could use your old primary or secondary o2 in the mean time. It shouldn't cause your car to die, but also is not helping you out not having it there. Then, check the fuel pressure at the fuel rail. This will tell you if your fuel pump and/or fpr are to blame. Given that the car will run briefly at startup, I wonder if the fuel pump is going, since it sounds like it will prime when cold, but then dies out possibly. The third possibility I see is the ECU is on the fritz, possibly (unlikely) from bad sensors, from the o2 simulator, or from a short somewhere. I've got my money on the fuel pump though.

ShoofIsLudin

the shop that did the t-belt said the timing was spot on after they "rechecked" it...? did they check mechanical timing (timing marks) or ignition timing?

Did the shop replace the timing tensioner? I'd make sure that ur timing belt is still spinning the crank AND cams. If ur car ran, shut-off, ran, shut-off, and now doesn't restart at all.... U need to start checking to make sure u have spark and fuel