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Author Topic: 1990 losing power under laod  (Read 5142 times)

Benbob

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1990 losing power under laod
« on: August 03, 2009, 05:58:00 PM »

Hi, I have a 1990 n/a OHC manual that will start and idle fine, but, when I go to drive (especially under anything over feather light acceleration)  it begins sputtering, spitting, misfiring, jerking, and losing power. Sometimes the Techoeter will smoothly drop by 2000 before beginning to accelerate for a few seconds, then repeat.

It has done this twice before but the problem went away by itself after sitting for a while. However, it seems to have set in permanently after driving to the other end of the island and back (approx 5 hours). although it made the trip ok - the next time I went to drive it, all hell broke lose.

I've replaced the fuel & air filters, spark plugs & leads, rotor & distributor, and put fuel treatment in.

Does anyone have any ideas what it could be? I'm at my wits end, maybe the timing belt slipping?
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Gostlrs

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1990 losing power under laod
« Reply #1 on: August 04, 2009, 04:12:00 PM »

1 can of B12 Chemtool.....
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Current Rides
2015 Nissan Frontier
2015 Chrysler 300
1990 240sx (SR20DET Swapped)
1992 240sx Convertible

Phillip

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1990 losing power under laod
« Reply #2 on: August 04, 2009, 05:42:00 PM »

Universal fix for everything motor?
Any compression check? How do the plugs look. Ever check the timing? Cracks or leakage in the intake system? The belt ever been replaced?????

Think first (what would cause this), check second (timing, etc.) and post third? No information no diagnosis possible!

My car ran like shit until I replaced the valve cover gasket and the wires! Been driving it 2-3000 miles a month ever since with 28 MPG mixed usage (for some reason the gas pedal sticks to the floor every time I drive it! Oh yea that's my foot stuck to it!)!
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Gostlrs

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1990 losing power under laod
« Reply #3 on: August 04, 2009, 06:02:00 PM »

mine did same thing when it was down to 1/4 take gas....chemtool fixed it..LOL

its my fix all
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Current Rides
2015 Nissan Frontier
2015 Chrysler 300
1990 240sx (SR20DET Swapped)
1992 240sx Convertible

Benbob

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1990 losing power under laod
« Reply #4 on: August 04, 2009, 07:15:00 PM »

Geez, do you you you work for chemtool or something?    And I replaced spark plugs, like I said before. I've checked my intake system, yet haven't found any leaks at all - and yes, I've sprayed the vaccum lines with crc too. I really don't know if the belt has been replaced or not.
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Gus Kelley

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1990 losing power under laod
« Reply #5 on: August 04, 2009, 11:35:00 PM »

Hey Ben!  There is a big list of things to cause this problem. You've covered some of them. It could be your primary voltage. Check what you're getting at the battery terminals. It should be 14+ volts if not then you don't have enough to fire properly and fuel pressure enough. Check your timing belt for slippage and if your car has a small nose crank then possibly check the crank pulley for slippage.  Good Luck !  Gus
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Benbob

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1990 losing power under laod
« Reply #6 on: August 11, 2009, 10:12:00 PM »

Thanks Gus, I had a quick look at the timing belt, and it does have signs of oil leakage and feels a little lose, when I have time I'll take it all apart and have a better look at it. (I didn't have time to take the belt cover off  properly last time)

Also, is there a way I can check the distributor? I may be the centrifuge mechanism inside failing, maybe.. but what I did notice was I had a loose vacuum lead going to the vacuum control unit, even when completely detached it didn't make a difference to the running of the capri, I clamped it on and it worked... for like 2 blocks then back to square one :/ Which makes me think that if the Vacuum control unit has no effect, maybe the timing advance in the actual distributor unit is malfunctioning.
Or in short, is there a way to test my distributor?  

Other than that, the voltage (at least on the dash) appears normal, but I can check.

Cheers,

Ben
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Gus Kelley

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1990 losing power under laod
« Reply #7 on: August 11, 2009, 11:18:00 PM »

Hey Benbob!  Hook up a timing light and get your timing mark located, cleaned and "Marked". remove the vacumn advance hose and check your timing. After checking then rev the engine while watching the mark. It should advance, this is checking the mechanical advance. Hook up the hose and you should notice a slight advance from that. If you don't notice a change in either check then you possibly have have bad springs in the distributor. Chime in for any further questions.  Gus
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Benbob

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1990 losing power under laod
« Reply #8 on: October 05, 2009, 09:51:00 PM »

Sweet, a bit late - put the capri on hiatus while organizing all my wedding stuff but... yup 'twas the distributor, put another one on and it goes nicely. I also cleaned and sanded the engine and fuel pump grounds which made a bit of a difference too!
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delhiboy3732

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1990 losing power under laod
« Reply #9 on: October 29, 2009, 04:01:00 AM »

I have a similar problem with my xr2. I also have a NA so will try and explain my issue with reference to that.

My NA runs freely and even seems like its running faster than the xr2. The xr2 seems like its being choked or something and when I go uphill with it, it starts bogging down untill I lower my gear and reduce my speed. The xr2 has new plugs and new wires. I even swapped the fuel pump and regulator from the na but still the NA runs like a champ and xr2 kinda runs choked.

The xr2 also has a new air filter and fuel filter along with new tranny and engine oil.

The car runs just fine otherwise. I drove it from Las Vegas to Seattle via Cali and it drove like it should however as soon as I used to approach hills it would start bogging down. Also, I noticed when it started bogging down the temp would also start to rise to about 225.

It also has a brand new water pump and radiator along with thermostat which has already been checked to be working fine.

Most people suggested it to be a choked cat. Any suggestions?
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Gus Kelley

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1990 losing power under laod
« Reply #10 on: October 29, 2009, 05:27:00 AM »

Hey Delhi! Could be leaning out from no fuel(fuel pump or filter). Or plugged exhaust system. There is a check on the exhaust. Something to do with disconnecting a vacumn line. Take it to a good smog shop or muffler shop and they'll diagnose it.  Gus
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delhiboy3732

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1990 losing power under laod
« Reply #11 on: October 29, 2009, 09:00:00 AM »

Like I said, fuel pump, regulator and filter have already been verified. Looks like I need to unscrew my cat and see what it tells me.
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Phillip

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1990 losing power under laod
« Reply #12 on: October 30, 2009, 07:30:00 AM »

How many miles on the XR2?
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delhiboy3732

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1990 losing power under laod
« Reply #13 on: October 30, 2009, 08:13:00 AM »

140K and 240k on the NA.
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Phillip

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1990 losing power under laod
« Reply #14 on: October 30, 2009, 08:51:00 PM »

Yank the distributor and check the springs.
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