Do you have factory plugs, gapped to factory specs?
Low power on 97 SC 80
- Thread starter Waggoner5
- Start date
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Wag,
Install a boost or boost / vacuum gauge, which will tell you if the bypass is sticking, hoses are leaking, etc.
I get similar mileage, but I'm running 35" truxus with the stock gears, which is eating up some of the boost (along with the additional weight - Bull Bar, Sliders, and rear bumper).
I have my boost / vacuum gauge measuring intake press / vac from the port on the backside of the intake plenum, like Dan.
When I mash the pedal, mine reads 7 psi of peak boost, and then 6 psi constant boost. I'm going to install the smaller diameter pulley like Dan this weekend, along with going back to the 285's. Hopefully this will increase fuel mileage and "seat of the pants" boost feel. Hopefully, I will find out from TRD what parameters they used when testing the SC in the next couple days.
Joe
Install a boost or boost / vacuum gauge, which will tell you if the bypass is sticking, hoses are leaking, etc.
I get similar mileage, but I'm running 35" truxus with the stock gears, which is eating up some of the boost (along with the additional weight - Bull Bar, Sliders, and rear bumper).
I have my boost / vacuum gauge measuring intake press / vac from the port on the backside of the intake plenum, like Dan.
When I mash the pedal, mine reads 7 psi of peak boost, and then 6 psi constant boost. I'm going to install the smaller diameter pulley like Dan this weekend, along with going back to the 285's. Hopefully this will increase fuel mileage and "seat of the pants" boost feel. Hopefully, I will find out from TRD what parameters they used when testing the SC in the next couple days.
Joe
R
robbie
Guest
Some mentioned the spark plugs, how recent is the tune up, fuel filter replacement? how many miles total on truck? Have you done a compression test on the cylinders yet? I would think the computer would kick some type of code if the converters are pluged, but a simple test is drill a small hole and hook a gauge up to it, this will take some thin metal tube for a foot or so then the hose to a guage, should not me more than 1-2 lb (lower the better) of back pressure if more may need to look at them. small hole can then be pluged with a screw. later robbie
It could also be from messing with the air intake the way you say. For one the mass air flow might not be reading right now and causing a lean condition, also, now you are not drawing air from within the fender, but the hot air the engine puts out. Hot air is not good unless you are a balloon 
Has the vehicle always been like this?
Yomama
Has the vehicle always been like this?Yomama
Waggoner5
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- #26
Ok, I ran a battery of tests today and basically found nothing out of the ordinary.
As of last Monday a complete tune up with all factory parts installed to factory specs, including plus, fuel filter etc. Today, I hooked up a boost gauge and found 7#s under load. Fuel pressure was withing Toyota spec. Driveshaft is back on, hubs locked and diff lock switch off. I have put the factory air box back in, but tested the IAT before and after with just the cone filter on the MAS and found that the temps were actually cooler with the cone filter. I account for the cool days we are having and the hood scoop pulling that cool air into the engine bay.
After testing everything I could there is still a little hesitation at part throttle, at any speed. Its not that bad, it just that I am just that picky. Also today I drove another 97 that I installed a SC on and it ran similar to mine maybe only slightly better. The only thing left is the converters or possibly something electrical that is intermittant enough that it won't throw a code.
As of last Monday a complete tune up with all factory parts installed to factory specs, including plus, fuel filter etc. Today, I hooked up a boost gauge and found 7#s under load. Fuel pressure was withing Toyota spec. Driveshaft is back on, hubs locked and diff lock switch off. I have put the factory air box back in, but tested the IAT before and after with just the cone filter on the MAS and found that the temps were actually cooler with the cone filter. I account for the cool days we are having and the hood scoop pulling that cool air into the engine bay.
After testing everything I could there is still a little hesitation at part throttle, at any speed. Its not that bad, it just that I am just that picky. Also today I drove another 97 that I installed a SC on and it ran similar to mine maybe only slightly better. The only thing left is the converters or possibly something electrical that is intermittant enough that it won't throw a code.
The ignition timing is?
Waggoner5, I pick fuel delivery as a culprit. Check back in a previous thread by robbie about bypassing the fuel pump relay. Although this would technically be "electrical" as you suspect. It sounds as if within a certain rpm range your fuel delivery is off. Also, have you pulled the injectors and had them cleaned and balanced? You may have one or more not fxning properly. Good luck.
Waggoner5
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- #29
I suspected ign timing to being retarded as I am, accounting for slow rpm, hesitation, etc, but it is to spec, by the book. I have thought it might be fuel delivery but still can't explain why, if lean, is there no detonation? I am going to take Robbies advice and bypass the fuel pump relay completely and see how things go. I have to say that it is running better after a thorough going over.
G
G
So you've checked a lot of stuff out and it all looks right...when was the last time you pulled and cleaned the TB?
I had a timing problem with mine because the idle was not right. What is the hot curb idle and does it ever fluctuate?
look for an exhaust leak prior to the O2 sensors. I had one at the Y pipe. It had split right at the crotch. This will allow O2 to enter the pipes and screw with your readings possibly making the truck run a little rich. Easiest way to tell is while cold cover it with soapy water and watch for bubbles while someone else starts the engine. My truck has really settled down since that split has been welded.
Waggoner5
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- #33
I looked at the O2s with the engine hot at 2k rpm and both are within spec. There is no sound of an exhaust leak but its possible. I have not pulled the TB or MAS and cleaned them yet but will do this weekend.
I cannot remember the exact idle hot, but the timing at idle is 11 degrees. I will check this tomorrow also
I cannot remember the exact idle hot, but the timing at idle is 11 degrees. I will check this tomorrow also
That timing spec is way off, it should be 3 degrees BTDC. Are you reading it with the datalink correctly shorted?
Waggoner - to elaborate on what Dan is referring to, if your TPS isn't set properly or not fxning properly, it'll never read "throttle closed" and so you won't be able to short the data link as indicated in the FSM. If your dash light isn't blinking you haven't done it. This would easily allow you to set the timing off quite a bit. This isn't all that uncommon either.
Mike
Mike
