Engine Loses Power At 3000 Rpm

[CDOOIT]

I have an 86 SVO with 128,000 miles on it. When the tach reaches about 3000 to 3200 RPM, the engine seems to lose power and sputter until it reaches about 4000 RPM. I have replaced the plugs, wires, and oxygen sensor. I replaced the fuel pump at 122,000. The EGO BOOST warning light is on. I have no idea what this means. Any help would be greatly appreciated.

[pegasus.v.o]

cdooit,
sounds like u have a vacuumm leak. Replacing the ones coming to and from turbo will most likely cure the problem. However, on a car this old it would be a good idea to replace them all.

[CDOOIT]

Engine Loses Power At 3000 Rpm

I have an 86 SVO with 128,000 miles on it. When the tach reaches about 3000 to 3200 RPM, the engine seems to lose power and sputter until it reaches about 4000 RPM. I have replaced the plugs, wires, and oxygen sensor. I replaced the fuel pump at 122,000. The EGO BOOST warning light is on. I have no idea what this means. Any help would be greatly appreciated.

[izzy]

About your engine loosing balls...

CDOOIT,

Ok, im not a big expert on SVOs just yet but after owning mine for almost 2 years, ive been through a lot <--- even your problem too. What the problem was on mine was the Throttle Position Sensor (TPS). Here is a link to how to set/check it: How to check/set the TPS Hope this helps. See what happens is that your supposed to gently cut and peel back a tiny bit if the wire insulation on the wires noted on the instructions (black and green?) and hook up an analog meter (needle type, not the digital read out one) and with the key on, engine off, slowly open the throttle by hand on the linkage and observe the meters needle. Its supposed to start out like a .90 volts (closed throttle) and end up somewhere at around 4.5 to 4.75 volts at WOT (wide open throttle). Watch carefully the needle and make sure that it goes up in a steady, smooth arc. ANY time the needle stops at all for just a tiny bit or even drops back down indicates a flat spot on the TPS and it WILL need replacement (around $40 @ NAPA, make SURE you take the old one off and take it with you to match it with the new one because the connector size/type varys between years). Just some advice you'll probably need a stubby, medium sized phillips tip screwdriver to remove the TPS and it will probably be easier to remove the Idle Air Controler (IAC) first to make some room, then re-install it once the new TPS is in. The stock TPS will not have the ability to adjust it but the new one will so you will have to get a DIGITAL voltmeter and follow the instructions on how to set the TPS. It basically sounds like you may have a flat spot on your TPS and the computer thinks the throttle is at a lower RPM that it actually is and therefore not sending enough fuel, only enough for the mechanical part of the engine to work, but no increased fuel injection action. I would suggest getting this fixed fast because the more you wait, the more you might damage your CATalytic converter (experiece).

anyway, that was my two cents like some says, hope it helps.
izzy

[CDOOIT]

I changed the vacuum hoses and that did not really seem to make a difference. I will check the TPS next and see if that is my problem. Does anyone know what the "BOOST EGO" light is for? Mine is on, and I don't know why. Thanks for the info.

[svobud]

the BOOST EGO is suppose to come on when 'over boost' condition is met (ie: 17.5 psi of boost), but that spot in the dash panel was also the location of the LOW OIL light. I really can't remember of the top of my head exactly what years had what - cause they seem sometimes vary though the years.

Sounds like you might be hitting over boost, Knock Sensor picking up detonation, and thus bogging out your engine when the computer kicks in. Could be a problem with the stock Boost Control Silenoid or your Wastegate is having problems....or the hoses as mentioned earlier. Could also be a clogged Fuel Filter, One Injector not performing up to snuff, or there MAY be a 'rattle' under the hood that the Knock Sensor is picking up (like a loose IC bracket).

Answer me this - does your boost peg out just before your engine bogs? Or, does the bog occur anytime your engine reaches 3k rpms?...like just easing the rpms up gradually.

[CDOOIT]

The engine bogs every time it hits 3k rpm. Even when I ease into the throttle. I just changed the fuel filter a week ago to see if that would help and it didn't make a difference. Thanks for the help.

[svobud]

and how much boost is it reading?

[richsvo]

For what it is worth, the EGO light on mine will come on when the oil is about a quart low. It took me forever to figure this out, but it does do it consistantly. I have never hit an overbosst condition in my car, but the low oil does sometimes happen, and when it does, that light is ON!

So, check your oil first (easiest thing), then look into the other things...

Rich

[izzy]

Answer me this - does your boost peg out just before your engine bogs? Or, does the bog occur anytime your engine reaches 3k rpms?...like just easing the rpms up gradually. [/B][/QUOTE]

My 85 does the boost peg out thing before the engine really pulls sometimes. Any idea why? Sometimes i can hear the Boost Control Solenoid making little clicking sounds a lot lately. You think that could be my problem? I have an aftermarket boost controller hooked up with a "T" on the vacuum line on the turbo (the usual way you do it) and i heard you can disconnect the BCS completely? Does that mean you disconnect the vacuum lines off of the BCS and then hook them up with a vacuum connetor and just leave the BCS there with nothing on it? Or will i need to do something else?

izzy

[svobud]

izzy - if you have an aftermarket boost control valve, then yes, you should have disconnected the stock BCS completely and put it on the shelf in the garage. There's no reason to have the two controls inline with one another. Could be your problem - but it sounds like you're getting a 'boost spike' - and it probably the result of the stock BCS's internal spring being old and worn out.

If your control valve is like mine, then you just pull the stock BCS off the car....and connect the 2 hoses to either side of the Aftermarket Boost Valve....and tune it in...

[svobud]

here's a pic Izzy...

[izzy]

boost controller

Bud,

Thanx for all the help. Just to let you know what i have is pretty much an industrial vaccum vavle that says good for 200 or so psi. I have a plastic "T" inline on the vacuum line that goes to the wastegate diaphram from the intake side of the turbo. On the T i have a vacuum line running inside the car so that i may control boost in the passenger compartment. What your saying to do is put everything back (remove that T) to the way it was, then remove the stock BCS and insert a vacuum T of the right size where the BCS used to be and then run my long vacuum line off of that T to the inside of car to valve right? I hope this makes sense but i can see how this works. What about the BCS? It is probably bad and is what is causing my problem, when i remove it, do i just disconnect it from the connector and leave the connector with nothing there? Will my car still run right even with stuff disconnected from it like the BCS?

izzy

[svobud]

you got it - and yes, remove the BCS (unplug it and remove). You will need to keep your prem fuel swicth on all the time now....and constantly run high octane fuel - unless you 'dial' your boost levels down to the 10psi level or lower.

[CDOOIT]

Hey guys, I am finally back. I changed the TPS and now it will only run for about a minute and then it will quit. From a cold start, it will start up ok. You can rev the engine and it seems ok. It will idle ok. But after a minute or two, it will quit. It begins to sputter and then it dies. It will start back up, but it immediately sputters and dies. If you let it sit for a few minutes, it will start up and run for about a minute and then it will die again. I also replaced the fuel pressure regulator, thinking that may be part of the problem. Any more suggestions?? Thanks in advance.