Vroomaster

This is what I've done so far to solve this problem:
1. grounded ECU-4 wires grounded
2. grounded pressure sensor
3. tested the 5/6 port actuatores (working)
4. tested crank angle sensor-good
5. added ground from '-' batt to chassis, then to top of block.
6. changed fuel filter
7. cleaned secondary injectors (home job-not that dirty)
The only things I can think of at this point is testing TPS and secondary resistance.
Any other ideas would be appreciated!

BTW what's happening is when I get on it, I hit something like a restrictor at 3800, but when I give it =< 1/4 throttle on the pedal, it will go over 3800 no problem, but if I go over, it just sticks where it's at.

HAILERS

I replied to your other post before I knew you did the above. Oh well. Heres what I think. The car will run up and over 80mph without the need for the secondaries to open, IF the throttle is gradually depressed and no sudden load is put on the car. IF you slam the throttle down to get to a higher speed, the secondaries will open around 3800 because of the ECU sensing the load. So that should explain why a slight throttle causes you no hesitation. It would appear that when you are hard on it, the secondaries do not open at 3800. But you figured that out. By the way, another thing happens at 3800 when hard on it. The primaries cut back at the same time the secondaries open. That explains the hesitation even more. Seems you need to work on the secondaries and see if they are opening under hard throttle. I know you have a meter. Put a wire tap on one of the secondary wires on the ECU and go for a ride. When hard on it, and at 3800 rpm, the voltage should drop from a steady 13volts(approx) to around 7 volts. That should give you a clue. The rear secondary wire is on the small plug and is the light green wire with a red stripe. The front secondary wire is the light green wire with a white stripe.

jbreezy

I've got the same problem on my 87. What tells the secondaries to open?

von

^^ and also on my 89GXL ONLY when light throtle does it hesitate. Does this mean that the primaries are not doing thier thing the same way the secondaries werent working for Vroomaster? Hailers?

von

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HAILERS

VON....Got me. Does not fit my preconceived notions.
JBREEZY....The car has to hit 3800 rpm and also have a load on it and I believe that is accomplished by the boost/pressure sensor leting the ECU know there is a heavy load on the engine. With judicious application of the throttle you can achieve over 80mph without the secondaries coming on line. With BULLINACHINASHOP application of the throttle they'll come on at 3800rpm. If you had two meters connected, one to the secondary and one to the primary, you'd see prior to 3800rpm, the voltage on the primary steadily drop from about 11.5 down to as low as 4v prior to 3800 being reached. When 3800rpm is reached the voltage on the primary will jump from the 4v to about 7v. At that same 3800rpm you'd see the secondary, which prior to 3800rpm would be around 13v, jump to the same voltage as the primary when it switched at 3800rpm i.e. the 7v mentioned above. Then both voltages will drop at the same rate. Those are not exact figures. Just close. EDIT: The above is what I see on a daily basis. I have two cheap RadioShack meters connected to the primary and secondary output wires. If someone violently disagrees, have at it. I have no books that tell me how this car works. Only what I've read on this site and what I observed on my car.

HAILERS

VON.....I can tell you this. If I pull both plugs off my secondary injectors, and go for a ride, I can pull 5000rpm if I use light throttle. And there will be no hesitation. So you can see that I can't relate to your problem. If I can think of something I'll let you know. I do wonder if yours could be a injector problem. I'd swap primaries with secondaries and see what happens. Seems if it were a primary injector problem there would be a change in the problem. Wouldn't throw money at it until I did that.

Ziggy682

I've had the exact same problem with my car. I'm waiting on some new injectors to come in so I can swap them to see if that fixes it.

In my car, over 3800 rpm with more than 1/4 throttle it bogs down bad. However this only happens when the car has been running for a while.

Thaniel

I think VONs may be in the boost sensor. I spent some time checking my boost sensor this saturday.

IF vaccume to the boost sensor increases the voltage output to the ECU decreases. Or if you are light on the throttle there is little voltage going to the ECU from the bost sensor (.5-1V) When hard on the gas the vacuume decreases voltage increases. Max I measured was 3.5V with no vac to the boost sensor (unplugged the vaccume line). High voltage tells the ECU that the motor is under load and under some conditions will turn on the secondaries.

The turbo the "boost guage" is run off the voltage from a very similar boost sensor. So I hooked up a volt meter and went for a drive.

I compared my car to my brothers and it seemed my car had lower voltage at part throttle then his car (low voltage, ECU thinks motor is not under load). My car had been doing the hesitation thing at 4.5K. Or at part throttle MY boost sensor was not putting out enough Voltage telling the computer I was in cruise mode when I wasn't. When flooring it the voltage would be high enough and no hesitation.

I think my boost sensor is going bad. I need to check into buying a new one.

I would reccomend Von pull the Vac line to the boost sensor and do a acceleration test to see if it changed anything.

Vroomaster

OK, I sould be able to hook up a meter sometime this week or weekend. Hmm, interesting....can't wait to see what I find! I think this will be the key to figuring it out my problem, now if I just could find a little time.....

HAILERS

There is another item that can give you a hesitation. Its the orifice that is supposed to be in the boost/pressure sensor line. Some call it a pill. If you do not have it, the lack of it will cause spikes in the signal from the sensor to the ECU causing the hesitation. The orifice should be found about an inch or so from one end. I replace that line without knowing a orifice should be in it, and had major bucking problems. Put the old line back on and all was well. Maybe thats the problem, maybe not. Just one more thing to look at.

Vroomaster

I pulled the boost sensor line off and found the 'pill', but the end that was on the block had a liquid that kinda smelled like fuel, so I tried blowing through it and it felt restrictive, so I'm flushing it w/ carb cleaner and hopefully clear it out. will update progress on my 86 na project

ps, it does buck as it hits the hesitation.

von

wow guys. Thnx alot. This was a new one on me. Great information. I will try all these things and tell the results.

Vroomaster

1. I cleaned the vac line to the pressure sensor, still seems restrictive to me , but at least it's clean.
2. I grounded the front tps
3. I checked the resistance of the secondary injectors. It's reading .6 ohms! I thought when they were bad, they read higher resistance, spec is 1.5-3.0 ohms. This doesn't sound like a problem, wouldn't it just cause the injectors to come on early? I may have read the ohmeter wrong, but I don't think so....

I didn't have time to hook up the meter and drive the car (weekend project), but I don't know if there's any point now given he resistance of the secondaries. Would switching the primaries & secondaries do anything?

HAILERS

Did they both read .6ohm ?????? You read that right at the plug, right? Does not sound right. Mine read right at 2ohms. You might go back and check it again. One pin to the other.

von

Ok...I just took the hose off the pressure sensor and took it for a spin. The car ran exactly the same. It still hesitated around 2k-3k under light throtle but also under say 40percent throtle in fouth gear at 2-3k as well. Nothing different than before though. Weird.

I took off the hose from the sensor side and put my finger on it. Thiers definatly vacume going to it.

Anyone? Mabey just grounding or bad injectors. I just got some good injectors today so I will put them in this week and give resutls.

Vroomaster

ya that's at the plug on each secondary injector. I'm going to do it again tonight and take a pic, I couldn't believe it myself.

Von: If it performs the same when on/off, wouldn't that indicate a non-functioning pressure sensor? I don't know, anyone else?

von

lol..I would assume so. Anyone???

Thaniel

Have you tried pulling the vac line to the boost sensor then reving the engine over 3800 and listening to the secondary injectors to see if the come on line? (one of the tests in the service manual) Also check the votage on the Brown with red stripe wire that is plugged to the boost sensor (engine off, ignition to on) Voltage should read 2.5- 3.5V atleast (one manual I have said 3.5-4.5 go figure). If you get voltage on the brown/red wire and runs the same with the vaccume line unpugged then it's not the boost sensor.

My guess it is bad wiring (grounds) or clogged injectors.

My car runs great with the boost sensor Vacumme line unplugged but gets horrid gas milage that way.

Hailers, What does the Orifice look like? My vaccume line hasn't been changed but maybe something happened to it. I wasn't sure the N/A had one.

HAILERS

I remember it being about an inch to two inches back from the end of the hose. Cheez. It didn't make much impression on me. I think oval and approx .040 hole in the middle. I shoved it in the new hose with a drill bit. The original hose had stripes of paint on the outside. Two stripes. Yellow and blue I think. Makes a difference on my car. Others have said they don't have one and have no problem.

Vroomaster

ya, Mines 86 na, there's one in there 1" from the motor side, can't tell shape, small hole in the middle. Not going to try and take it out, looks like it be a pain.

von

THEINEL.....Actually I have an N/A and thiers ONLY a vac line and NO PLUG... I dont have a connector with wires going into it is this normal??? I changed wiring harneses a wile ago and cant remember if thier originally was one.

Vroomaster

should have wires/connecor (4 wire I think) pluging into it.

HAILERS: Haven't had time to recheck the 2ndairies, but what your saying is I can rev up to 7k rpm w/o 2ndary help as long as I go easy on it? I am able to get to 7k rpm no problem, just can't give it more than 1/4 throttle.

HAILERS

Yeah. Thats what I am saying. Easy on the throttle and you should be able to make it into the high rpms without stumble, because the secondaries don't come online at 3800 unless the boost/pressure sensor senses a high load, which it won't if your lite on the throttle. Something is odd on Von's car. He says his boost/pressure sensor has no plug on it, just a vac line. Must be looking at the wrong item. The boost/pressure sensor is rectangular in shape, black, and has a single vac line and electrical connector. Its located in front of the r/h strut tower. And oh yeah, that .6 ohm just can't be worth a darn. Everyone of my spares is 2.1 ohms.

von

In my case hailers the pressure sensor is black , rectangular, on the left side strut tower looking at it from the engine side and has 1 vac liine going into it.

I will take a picture of it soon.