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CDOOIT
11-19-2002, 09:54 PM
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
11-19-2002, 10:18 PM
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
11-19-2002, 10:24 PM
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
11-20-2002, 12:24 AM
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 (http://svo.driversfound.com/showthread.php?s=&threadid=11) 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
11-20-2002, 04:49 PM
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
11-20-2002, 07:52 PM
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
11-20-2002, 10:58 PM
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
11-20-2002, 11:58 PM
and how much boost is it reading?

richsvo
11-21-2002, 01:58 PM
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
11-22-2002, 01:49 AM
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
11-22-2002, 07:58 AM
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
11-22-2002, 08:00 AM
here's a pic Izzy...

izzy
11-23-2002, 07:45 AM
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
11-23-2002, 10:03 AM
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
11-25-2002, 09:17 PM
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.

SVOeric
11-25-2002, 10:28 PM
I'm just asking, so don't go off...

Did you follow the procedure in the FAQ to set the TPS?

it's not a plug and play thing, it has to be adjusted..

svono50
11-26-2002, 11:32 AM
CDOOIT, If your TPS is new and set correctly, it sounds like you may have something bad in the fuel system (i.e.- bad fuel pump or injectors). Start by checking the system pressure. Get a pressure gauge on one of the schrader valves and see what pressure your system is showing under various conditions, if you can keep it running.

When you turn your ignition to run the pump should prime the system and the pressure should slowly bleed down. If it drops off like a rock, you could have a faulty pump check valve or bad fuel pressure regulator (new one's have been known to be bad). Let us know what you come up with from here.

CDOOIT
12-08-2002, 08:47 PM
Hey guys, I finally have found time to get back to you. Since my last post I double-checked my TPS and it was reading between 0.91 and 4.70, so I guess that it is set okay. I also changed the fuel pressure regulator again and still no change. I changed the distributor cap and rotor and checked the ignition module and it was okay also. I have not been able the check the fuel pressure yet. I did have it put on the computer the other day and it seems to be pointing to the VAM. Does anyone know if a bad VAM could cause me this kind of problem? Is it common for these to go bad? When I start the car up now, it will run fine for about 80-90 seconds and then it will sputter and die. When you start it back up, it will run for 3 or 4 seconds and sputter and die. If I let it set for a few minutes, it will start up and do the 80-90 seconds thing again. I have been told that it sounds like an electrical problem, but I just don't know. It is really getting annoying. I hope someone out there can help. Thanks again for all of the help so far.

svobud
12-08-2002, 09:04 PM
Originally posted by CDOOIT
I did have it put on the computer the other day and it seems to be pointing to the VAM. Does anyone know if a bad VAM could cause me this kind of problem? Is it common for these to go bad? .

I've never had one go bad on me - so I couldn't tell you. I will tell you that Mike Ray (fellow Board of Director) had one go bad on him once and now he doesn't travel long distance without a spare in his box of parts (along with a spare TFI, TPS, and other assorted goodies).

SVOeric
12-08-2002, 10:15 PM
yea.. they don't go bad that often.. I would suspect wiring before I thought bad vam.

I have a test procedure around here somewhere for a vam...
let me find it, and I'll post the link..

coupe
12-10-2002, 05:32 PM
I've seen a VAM go out on a 91 turbo Capri (like a miata, but faster) and it caused all sorts of trouble beyond idle problems (ie: glowing orange turbo!)
My first thought on your situation was : Did the Idle-control solenoid get put back on correctly & with a gasket. Those things are a bit pesky on SVO's and 5-liters for that matter.:(

CDOOIT
01-01-2003, 01:30 AM
Hey guys, good news to finally report. My problem finally turned out to be a bad fuel pump. The gas tank on my car was really nasty where it had set for about a year before I bought it. The stuff floating around in the tank killed the new pump I had put in it. So I pulled the old tank and replaced it with a new one and also installed a new fuel pump. Happy to report that she is running great again. Thanks for all the help and suggestions!

svobud
01-01-2003, 10:54 AM
excellent! glad you got it fixed! I really like that you came back and told us what it was too ... thx

svopantera
03-17-2005, 08:42 AM
Originally posted by 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.

Just curious, why you have to keep the premium fuel switch on?

SVOBart
03-17-2005, 01:23 PM
Originally posted by svopantera
Just curious, why you have to keep the premium fuel switch on?

Because it also signals the ECC to use the premium fuel calibration which uses a more agressive timing and fuel curve.

svopantera
03-17-2005, 02:01 PM
Thanks for that info.