Engine Bogging during acceleration

[daewooluvr]

The past few days I've noticed a miss here and there. Then this morning the engine would bog down so much that I could barely make it to work. It seems to only do this in gear and when I give it gas. When I'm in park or neutral it doesn't do it.
I was initially thinking it was spark plug wires but if that were the case it would do it all the time.

Now I am leaning towards a blocked catalytic converter, clogged fuel injectors, blocked fuel filter. Any thoughts? Also how would you test each to narrow it down?

[daewooluvr]

Leaning more and more towards catalytic converter

[daewooluvr]

Just got off the phone with the auto repair shop and they're saying it's probably a transmission issue because if it idles and revs fine in park or neutral it cannot be the cat.

Any thoughts?

[PrecisionBoost]

In my opinion they are not considering all the options, at idle the car is not under load, even if you rev the piss out of it.

Under load the bogging could be fuel related, fuel filter or fuel pump

It could also be ignition based as it will change more during load than if at idle

I don't know about the Catalytic converter being blocked, again under load it will create lots of back pressure.

If it's an automatic then yes, it's possible there might be a transmission problem

If it's a manual then odds are you would smell a slipping clutch ( rotten egg )

[daewooluvr]

In my opinion they are not considering all the options, at idle the car is not under load, even if you rev the piss out of it.

Under load the bogging could be fuel related, fuel filter or fuel pump

It could also be ignition based as it will change more during load than if at idle

I don't know about the Catalytic converter being blocked, again under load it will create lots of back pressure.

If it's an automatic then yes, it's possible there might be a transmission problem

If it's a manual then odds are you would smell a slipping clutch ( rotten egg )

I'll try to drop the exhaust to see if it is the catalytic converter. I'll also check the fuel pressure on the rail to see if that is dropping.

[kosuruvr]

I also seems to be in the same boat. However, with my car problem is not severe. It is as though some unknown force is not allowing the car to move. I noticed this problem occasionally over the past 1 month, but last week I gave it for servicing and a silencer replacement. After I got it back I noticed that the engine misses occasionally. Then mechanic was called again who said that petrol might be contaminated with water and other debris. So I got the fuel lines and tank cleaned, changed fuel filter and then got the injectors thoroughly cleaned. Now, the engine starts fine, but does not take pick up and accelerate. Engine however runs smoothly while standing. What could be the problem.

[Trey05Woo]

If i had to guess i would say fuel pressure. the engine might be running lean and stumble under load, but produce enough power to rev and maintain at idle. i really really doubt you have a trasmission issue infact its mind boggling that a shop would even tell you this without looking at the car or checking trans pressure! but i'm not here to judge just to help lol, so chk fuel pressure and remembrr to run multiple tests. at idle, drive the car to replicate the fault, and also a sitting test. fuel pumps can be a bitch and fail intermittenly. pressure should be steady and raise under acceleration. drive around with a gauge to windshield so u can monitor it. also park the car and let it sit for an hour turned off, the pressure should drop if at all no more than 10psi.

[Puddle31]

not a mechanic but I agree with Trey. it sounds more fuel related than transmission.

[MMamdouh]

put it in third gear while doing 30 km/h and floor it... if it bogs down like hell then it is the spark plug wires... revving in neutral won't reveal any problems as their is no load whatsoever

MMamdouh

[Puddle31]

MMamdouh, what does that do that would make it different from a possible fuel problem? is that some special procedure?

[daewooluvr]

Well all it turns out that it was a blocked catalytic converter. I knew it when it happened. I don't know what I let that shop make me second guess myself.
I disconnected the exhaust from the manifold to get it home. You should've heard how loud that was lol.

Probably looking to replace the whole exhaust.

[PrecisionBoost]

Good to hear you got it sorted out.

[daewooluvr]

split to new topic
http://www.daewootech.com/forum/viewtop ... =1&t=13740

[MMamdouh]

MMamdouh, what does that do that would make it different from a possible fuel problem? is that some special procedure?

i don't know the technical explanation for that but it seems when you demand massive torque at such low speed and high gear the electrical system is some how loaded to the maximum and if their are any problems they will show up clearly even if those problems are not that apparent under normal conditions.

i recon the fact that this test is done at very low RPMs, fuel system is not at maximum load so it is somewhat not that effective factor here

MMamdouh

[Trey05Woo]

Interesting that the car would rev normally at idle with the clogged catalyst. Surely it had to have sounded different almost muffled even if it did not hesitate at idle...

Dropping the exhaust is a sure way to test, but I normally just remove an 02 sensor, works just the same and you can isolate which cat is the cause on multiple cat vehicles. It's also safer open headers is a fire hazard loooool.

As far as fuel and spark troubleshooting goes, both will cause similar faults when not working to specs. Truth be told it takes many years of experience to seperate the two. One tell tale sign ignition is at fault is noise. A faulty ignition system will cause pinging, or ticking (wire arching) and "misfire" the true meaning of the word. over the years misfire has evolved to mean bucking, dead cylinders, no spark, no fuel injection etc. But in the old days misfire was poping, fire in the intake and out the carb, burn your eyebrows out kinda thing.

In the modern era the correct way to diagnos a misfire is fuel/ignition system. Normally the former is easier to test, so its always best to start there and progress...