Engine bogs on load

Engine bogs on load

Postby tman7 [OP] » September 8th 2010, 4:58am

I have a 93 Astro with TBI. Lately I have experienced a hesitation when accelerating. It tends to happen after it has warmed up. In neutral the engine revs up without any trouble but in gear Its a struggle to get up to speed. If I hold down the pedal long enuff eventually it will begins to roughly accelerate. I have checked over the engine and cant see anything obvious. I did a resistance check on the IAC to determine if its ok, it was. Tho I dont know that a bad IAC would cause this. No trouble codes, except for once when I floored the pedal (took about 10 seconds before the engine finally began to accelerate.) threw a lean exhaust code. I checked the fuel filter a couple of months ago and had the fuel pump changed too.

I would be grateful for any suggestions as to possible causes.

Thanks
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Re: Engine bogs on load

Postby cowboydan » September 9th 2010, 12:48am

tman7 wrote:I have a 93 Astro with TBI. Lately I have experienced a hesitation when accelerating. It tends to happen after it has warmed up. In neutral the engine revs up without any trouble but in gear Its a struggle to get up to speed. If I hold down the pedal long enuff eventually it will begins to roughly accelerate. I have checked over the engine and cant see anything obvious. I did a resistance check on the IAC to determine if its ok, it was. Tho I dont know that a bad IAC would cause this. No trouble codes, except for once when I floored the pedal (took about 10 seconds before the engine finally began to accelerate.) threw a lean exhaust code. I checked the fuel filter a couple of months ago and had the fuel pump changed too.

I would be grateful for any suggestions as to possible causes.

Thanks


couple questions, when were the plugs changed last? pull one and have a look. does it knock or tap? what's the milage? how long have you had the van for? how long ago did you throw the lean code and was this fixed? was the change sudden or is it something that has gotten worse over time? i know it's more than a couple. id be happy to throw some ideas but saying fuel or timing would be vague
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Re: Engine bogs on load

Postby Leeann_93 » September 9th 2010, 2:00am

Besides the standard tune-up stuff, have you tested the TPS?
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Re: Engine bogs on load

Postby tman7 [OP] » September 9th 2010, 4:54am

Thanks for your replies.

I have had the van about 4 years. When I first bought it I had a rebuilt engine put in. I have put about 50K miles on it. Since I had the engine installed I have probably replaced nearly every compnent on the engine. Spark plug wires (sometimes 4X a year), OXY sensor, ignition coil and module (twice), map sensor, TPS. Fuel injecters (twice). EGR valve. Pressure regulator. I have also put on a TB spacer, one that I saw talked about here on this forum. Havent seen alot of difference with it. The plugs havent been changed in year, I think. Just checked and adjusted the timing, was 5 deg advanced. Replaced the TPS, but the way its acting I am going to check it just to be sure. The odd thing is it runs fairly decent untill it warms up. Causing me to think it is likely to be a sensor. But if it is why no trouble codes? Havent seen the 44 code (lean) again.

I think I began to notice it a week ago and it has gotten steadily worse. I now have to touch the pedal just right and keep it there if I want to be able to get up to speed and very slowly at that. Occasionaly I get a soft backfire and something that sounds like a small quick air burst comming out the TBI.

One thing you should know, I have a carpet cleaning machine installed in my astro. It is a power take off unit. So the van runs at high rpm while standing still. Although I crack the hood. The lack of air flow is very hard on engine parts. Hence why I have to replace parts so often.
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Re: Engine bogs on load

Postby cowboydan » September 10th 2010, 3:07am

most people use diesel engines for your purpose. lean codes tend to be plug related when used for such applications. running worse after warm up doesn't scream sensor, if the sensor fails or looses communication it throws the code. if it picks up detonation. right now it shows lean and hasn't tripped the knock sensor yet. i'm guessing all those changed parts tells me that this problem your having is new and you haven't expierienced it before? so if that is true, and it runs worse when warm with a lean code... it won't come back on if the computer is able to compensate. that lean code is probably your best answer. i might invest in diesel or a seperate generator to power the unit.
high rpm with electric load is milage. your lean code is likely detonation and it could be cooling related, but i have a feeling your going to be replacing a bit more than an accesory this time round. i personally think it is internal. at best timing chain.... based on the popping and backfire. sorry i can't give more, you have changed parts everywhere and more than once in 4yrs. this is the best i can do.
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Re: Engine bogs on load

Postby choppedndropped » September 10th 2010, 4:30pm

I would suggest putting your timing back to normal and check your fuel pressure. Any other symptoms? Blowing any smoke or anything?
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Re: Engine bogs on load

Postby tman7 [OP] » September 11th 2010, 3:16am

Well I think I may have found the problem. I pulled the fuel filter and the internal piece that acts as the filter had come loose and was ratteling around inside the metal casing. So, for who knows how long unfiltered fuel was alowed to travel to the engine. After replacing the filter It ran real good for a couple hours and then started running a little rough again. I'm thinking something nasty is stuck somewhere in the system.
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Re: Engine bogs on load

Postby SafariBrutus » September 11th 2010, 4:42am

Your problem sounds very similar to the one I had. My 97 Safari would run fine when cold, but after it got warm it would lag and hesitate and wouldn't accelerate unless you held your foot 'just so' on the gas pedal. I replaced all kinds of parts, including the fuel pump... but nothing helped. Two years of looking for the problem, a year driving around with a Scanguage2 hooked up, and zip. No codes, no nothing. Frustrating... very frustrating. (Insert bad words here!)

Last week it finally got so bad I had to take the van to a dealer to get fixed. Was in a different city so had never been to this dealer before. They worked on the van for three hours before they figured it out. A worn gear in the distributor, not bad enough to cause problems while the van was not under load or cold, but when it got warm and had a load... it started acting up. They replaced the distributor, I paid the (big) bill, and I love my van again. Runs fine, no problems, and I'm not afraid to accelerate with my boat hooked up. And I'm getting better gas milage!

for the tech people:
When my van went bad it threw two codes. P0339 and P0341. The mechanics fixed a broken vac line, shimmed a sensor that was hitting a camshaft, tied up a loose wiring harness, and replaced the entire distributor.
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Re: Engine bogs on load

Postby Blueastro » September 18th 2010, 6:05pm

My 97 Astro exhibits some similar problems to this one with a worn distributor gear. It only shows up under a strain of going a little faster for several miles (maybe 40 or more) or hauling a trailer. Would it not show up more consistently or more often ? It seems to put a lot of back pressure on my catalytic converter as well, like it is dumping a lot of gas or raw gas into cat, and then when I shut it down the cat is popping and making a hissing or a pressurized noise, until the gas burns off over several hours. I did replace the cat, thinking the cat was stopped up. It really did not help much , if any when it happened again a few weeks later. SO it goes thru these spells, and will run ok later until the next episode .

I have seen similar problems on here, but not sure if the distributor is the problem. Any more sure way to tell if it is ?

Thanks for any help, you can give me.
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Re: Engine bogs on load

Postby RECox286 » September 30th 2010, 2:49am

One of my 93's (TBI) feels like I'm running on a washboardwhen I accelerate, only opposite, it only does it in open loop. When she warms up, it drives fine. So far I've tried jumping out the ground at the temp sensor to batt ground. No joy Any thoughts?

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Re: Engine bogs on load

Postby rollinhome » January 23rd 2011, 8:42pm

I have a similar running condition, intermittent bogging. over 2 years now. I have change wires, plugs, distrib cap, tested coil and module. code indicated poor performing cat though o2 sensors tested ok, so when operation go worse while on the road, i cut the cat out only to find no change in the operation.
I believe it is fuel system related though at first i did not as i had tested and found correct fuel pressure and changed the fuel filter.

I can run it on the highway for 5 min, sometimes more, it will loose power (though idle most times), i shut it down for 10 seconds with van in neutral, fire it up an drive again for 5 min. this is how i got it home, more than 120 miles. it was mid day on a sunday
and nothing was open. since then my mechanic was sure it was the computer, it wasn't.

I had parked it on an angle which simulated being out of fuel and when i raised the tank fuel level and started it, it ran worse and so
i believe there is something wrong with the fuel delivery system.

anyone have an issue with the fuel pump pickup screen clogging, fuel regulator issues or other fuel related problems.

I am out of time, chicago requires emission testing, which i fail and will not allow registration renew-ell with out same and my reg.
has expired. help!
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Re: Engine bogs on load

Postby Phantom » January 23rd 2011, 10:41pm

Your fuel pressure and it should be about 58 psi at idle , if it below 55 it should be replaced .when you replace pump replace pick up screen with it . There is and old trick that baffled people by putting in the gas tank maple tree leaves , as the pump suction increased it would draw the leaf to the port and cover it up greatly reducing the amount of fuel pumped and causing engine to die ,
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Re: Engine bogs on load

Postby mkj54 » January 24th 2011, 12:45am

Your going to need to replace the cat to pass the test. I suppose you knew that. What I've done when I suspected a fuel problem is drive with the doghouse off and a fuel pressure gauge hooked up and checked fuel pressure when the problem occured.
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Re: Engine bogs on load

Postby Phantom » January 24th 2011, 1:13am

mkj54 wrote:Your going to need to replace the cat to pass the test. I suppose you knew that. What I've done when I suspected a fuel problem is drive with the doghouse off and a fuel pressure gauge hooked up and checked fuel pressure when the problem occured.


Yep x2 on that , then you can see exactly when the problem occurs.
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Re: Engine bogs on load

Postby rollinhome » January 24th 2011, 5:25pm

Hey All, it feels like the maple leaf condition though that leaf would have disintegrated by now, maybe something else is in there
being sucked up and onto the pickup screen.

I have checked the fuel pressure twice, with the dog house off, during the conditions occurrence. My thought is to change out the fuel filter a 2nd time cuz during the first replacement the fuel line showed a lot of black goop on the tank side of the filter, it ran better for a while though has gotten worse. after the filter change i will again test fuel pressure and possibly pull the tank down to see if something is gooping up the fuel delivery.

i realize i will need a new cat, any experience here with the options from summit racing. I expect i will do that repair after i have confirmed that the first problem is eliminated.

thanks for the support, i really enjoy the size and power of these vans though i am puzzled on this one feeling like this is the last straw. I don't mind these puzzles so much around town, though i like to van camp and have not been able to use this van for that purpose for some time now.

ray
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Re: Engine bogs on load

Postby Phantom » January 24th 2011, 5:34pm

Black goop from the tank side ,,possibly a rotting corpse in the tank? :lol:
There may be sludge build up in the tank , maybe using a product like Stabil , or Lucas fuel system cleaner may help or if real bad maybe drop the tank and get it cleaned thoroughly
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Re: Engine bogs on load

Postby paintdrying » January 24th 2011, 6:17pm

Side note, not sure how strict you emissions test are, but maybe it will pass as is? You may get a retry free if it fails.
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Re: Engine bogs on load

Postby rollinhome » January 28th 2011, 8:35pm

the plan is to recheck fuel pressure, during the loss of power cycle, with the rental tool from autozone, then drop the tank, make sure it is clean, change the filter again.
what kind of symptoms would a blocked return line produce, maybe while the tank is down i should blow some air through that line.

of course this time of year is only good for producing ice sculpture.

emissions retests are free
r
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Re: Engine bogs on load

Postby rollinhome » February 27th 2011, 6:49am

So, it is winter in chicago, which means if i am working on the van in my unheated spaces, it needs to warm a bit, and it has. I found that the fuel pressure is 52/53 at idle. It is the same whether the van is running smooth or bogging out. When it does bog,
i shut the car off for 5 to 10 seconds, it will run smoothly again though will again bog out after 3 to 10 minutes. once i went
through this pattern for 200 miles to get the truck home.

so, if the fuel pressure is low, why does it run well for a good bit of time then begin to feel like it is starving for fuel and what part does shutting down/off the engine and then restarting play in it running well again.

I can accept the pump being the cause, i don't understand how turning the engine off and on changes anything with the pump,
this part of the dysfunction has always made me feel it was something else.

any thoughts?
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Re: Engine bogs on load

Postby cowboydan » February 28th 2011, 1:23am

what was the code? poor preforming cat? what if you replace the cat, disconnect the battery for a bit, what have you got to loose? you need the cat anyway. if you test the sensors, the only thing it will prove is that the sensors work fine, and they are picking up a malf. those are my thought's. when you tested the coil, what color was the spark?
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