Subarutex Posted October 2, 2003 Share Posted October 2, 2003 OK, here is the car: 87 RX w/ intercooler and bov. Just added a spider intake. Problem: While driving when I stop accelerating and go to just cruise, the engine will jolt back, like i'm deaccelerating. Holding back. If I keep this even pedal pressure, it will surge back for a second, then hold back again. I have tried: Thought it was turbo lag because the BOV was vented to atmosphere. I added a bypass to it, so it dumps now right before the turbo inlet. I also thought it might be the way I had the throttle cable done. I changed it. Better feeling pedal now, which is a plus, but still the weirdness. Ideas: Could it be the idle sensor? Poorly adjusted, or bad wiring? Could it still be really bad turbo lag? Thanks for the suggestions. Link to comment Share on other sites More sharing options...
calebz Posted October 2, 2003 Share Posted October 2, 2003 Any error codes? Mine did that when my EGR was on the fritz. still does it, but not as badly Link to comment Share on other sites More sharing options...
mcbrat Posted October 2, 2003 Share Posted October 2, 2003 I had similar symptoms with a Chevy Blazer 4.3 Vortec, and it ended up being the EGR valve, and some fuel pressure relief valves that were cuasing me to lose fuel pressure.... Link to comment Share on other sites More sharing options...
syphon Posted October 2, 2003 Share Posted October 2, 2003 Dude, based off these replies, I'm starting to think it could be related to that hose that you pinched off towards the bottom of the engine (I don't recall what it was related to but I think it was EGR). I bet since it still has a minor leak, it could be causing your problems. You don't think it could be related to removing the smog cannister do you? Are all those connections on the intake plugged up? Should they be plugged up in the first place? Just some thoughts... Link to comment Share on other sites More sharing options...
rallyruss Posted October 2, 2003 Share Posted October 2, 2003 pinching off the vac. line to egr will just make the egr inop. I have a similar problem on my gl10 I have checked the TPS, airflow meter, O2. I still need to check to see if the egr is being applied early that might cause what you describe. posible loss of spark? probably not. if your problem is like mine it goes away under throttle? hope we figure this out. I have seen others post about th same thing. Link to comment Share on other sites More sharing options...
nomica Posted October 2, 2003 Share Posted October 2, 2003 After driving 300 miles, i came up with these ideas. Like Jay said, it could be the slightly leaking EGR line, or the lack of smog canister. I'm gonna make some phone calls. This is Tex, btw. Link to comment Share on other sites More sharing options...
Skip Posted October 3, 2003 Share Posted October 3, 2003 Tex, how did you solve the TPS problem, this could be related. Do you have any gauges on this radical ride? I do not know what you mean when you say "idle sensor" Do you by chance mean "idle switch"? Link to comment Share on other sites More sharing options...
Adam N.D.J. Posted October 3, 2003 Share Posted October 3, 2003 I've got the same problem on my 2.7 Although mine is at about 1/4 throttle. I've tested the TPS, and I know it's bad. If you test the resistance across two of the terminals, (not sure which ones they are on the 1.8's TPS), but as you open the throttle, the resistence should go down smoothly. This works better with either an analog guage, or a digital that you can record high/lowest on. For example the resistance should go from like 10 ohm to 1 ohms smoothly. If it goes from like 6 and jumps to like 10 or 1 then 4, you've found the dead spot. Get a new one. And the computer will seldome catch this problem, specially since the voltage to the computer is suppose to run from like 1v-5v, so if it doesn't go outside these values, even in a wrong position, the computer won't trigger a code. Link to comment Share on other sites More sharing options...
Subarutex Posted October 3, 2003 Author Share Posted October 3, 2003 Skip: First I tried to wire up the TPS that was on the spider to my harness. This didn't work. As it turns out, NA and Turbo TPS's look different on the inside. NA being the one that was on the spider, only had one sensor arm on the inside. The one off my old manifold had 2 arms. So then I examined the differences besides the arms. Only one i found was the direction of rotation. So, to solve my problem, i took the cover off the original TPS, drilled a hole in it and mounted it so the direction of rotation matched. As far as guages, i have the following: Stock gauges, all functioning. Autometer boost gauge. Apexi Turbo Timer which has digital voltage gauge and 2 views of the A/F ratio. One being the voltage, and one being the theoretical values those relate to. I also have an Apexi SAFC (Super Air Fuel Controller). This has digital RPM, digital air flow, and digital throttle gauges. In my FSM, the black box on the side of the throttle body is called the Idle switch...or Idle sensor, can't remember which exactly. Also in this same unit (with a seperate cylindrical connector) is the TPS. I tend to interchange idle sensor, and idle switch I guess. If i had the tools, i'd test the resistance of the TPS, unfortunately I don't. What tool would you use? I assume this same tool would be widely used in other aspects of wiring, so it might be useful to pick up. Average price? Thanks. Link to comment Share on other sites More sharing options...
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