Thaniel

Sounds like it. Rh shock tower on the front side. One 10mm bolt holding it to the shock tower. Vac line going to vac port right above the ACV on the intake manifold.

Has to have a electrical connector going to it or it won't do anything. Check on the bottom side of the pressure sensor there should be a spot for the 4 wire electrical plug.

Vroomaster

OK, I just bought a new multimeter for this purpose. The one I have is a radio shack cheapie that has been banged around for about 8 years so I'll take a reading tonight and take a pic of the reading.

Vroomaster

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Bump so it won't get lost

Vroomaster

OK, I checked the resistance of the 2ndaries w/ the new multimeter and it checks out fine @ 2.4ohms, i checked it again w/ my old one and it still read .6! This is wierd cause i checked the crank angle sensor & both meters read the same. hummm
Anyway, I'm can't find the selenoid resistor, Haynes said it's on the drivers side tower, but can't find it anywhere, anyone know offhand where it might be located and how many wires go into it? Thanks!

Vroomaster

results:
2ndaries: 2.4 ohms
Selenoid resistor: 6.1
BAC: 12.1 (i think)

so far, everything's w/in spec
Sounds like an ECU problem, but I'll have to wait til this weekend to find out.
OH, does anyone have a pic of clean injectors? When I romed mine, they looked fine, no gunk on them or anything.

Vroomaster

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Thaniel

If I understand what you are looking for, it is in the right front corner under the air box. Have to pull the air box out to get at it I believe.

Make sure your wiring is good from the injectors to the ECU. Mine had some problems years ago and I ended up replacing the whole wiring harness.

Vroomaster

thanks, I found it. Just need to hook up the meter to check the voltage going to the secondaries.
How do you check the wiring from the injectors to the ECU? just visual?

von

Hey guys. i just plugged my dam pressure sensor in this morning....AFTER 6 MONTHS....I love this forum.

?... I accidently plugged the sensor plug into the cold start thingy next to the charcoal canister. Does this cold start thing.( or whatever it is) send any voltage out. Im wondering if their was a chance of shortage.

Anyways. I think I noticed a difference but it is hard to tell. I think I got rid of my missfire I had. Not really a missfire but a jerk every second when im cruising or deccelerating. Thats gone but the hesitation is still thier so im betting its injectors.... THNX ALOT GUYS.

Vroomaster

HAILERS: I'm going to do the meter thing tonight so I had a quick question: If the voltage going to the secondary injectors does not drop to around 7 or so, then what would be the problem? ECU or wiring to the ECU? I suppose if it does drop to 7, then it's the injectors.

Thaniel

I was EXTREMELY busy at the time and sent it to the dealer. The wiring was all hard and would crack easily. I pealed back some of the insulation and the wiring inside was coroded! I tried splicing in some bits (didn't do a good job, I was in a hurry) so I said screw it and bought a spankin new harness and put it on. Worked great until recently I am getting this hesitation thing.

If I had to do it all over I would have just run new wires for the critical connections.

Vroomaster

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HAILERS

The injectors to the ECU???????? Get your meter and take off the small plug on the ECU. Then look for 12v at each injector input. Leave the plug connected if you want and go in the back of the plug. If you have 12v the circuit is complete. Its more than likely good if you have 12v, but there are some exceptions that are not worth mentioning, like maybe one strand of wire making the circuit blah, blah. Don't forget the basic stuff like someone having spliced in a new injector plug and having done a bad job on the splice. Can't see the splice under the covering but you can ohm out the wire from end to end and manipulate the wiring around the spliced area while looking for a break in continuity. Same can be said for manipulating the injector plugs while ohming the wiring. Mabe this, maybe that.

Thaniel

Thank You HAILERS!! Yes I know it has been awhile but I have been really busy and or sick. Turns out this was the problem with my High RPM hesitation. I Found there was no orifice in my boost sensor vacuume line. I made one by drilling a 1/16 hole in a bit of plastic and shoving it in the end of the line. Hesitation GONE!!!! I am so happy. This makes sense as the hesitation started after I had worked on the car. I had cut the end off that line because it was cracked. Must have had the orifice in it. =(

It has been raining here and on wet roads it'll spin the tires in 2nd gear aprox 5000 rpm. Hasn't done that before. Maybe my exhaust changes are worth something after all.

While I was testing things I measured the Voltage for the boost sensor. Since the hesitation was worse when it was cold out I also put the sensor in the freezer for a few hours then measured the values (no change). Anyway here are the values if anyone ever wants them.

Inches Hg applied--Volts output (with Key on engine off)
0--3.52
2--3.19
4--2.92
5--2.80
7--2.54
9--2.28
10--2.11
12--1.82
15--1.4
18--.97

Also:
At aprox 3.15 the split air solenoid would turn on.
At 800 rpm the engine pulled 16" Hg at 1500 RPM pulled 18in Hg.

BY the way the Haynes manual for checking the boost sensor is wrong. (it says pull 3.9 in Hg on pin D which is an electrical connector, also says voltage should be 3.5-4.5 which is wrong. Should be 2.5-3.5 V with 3.9" Hg. 3.5-4.5 with no vacuume at all).

Hope all this helps someone else. And once again I am Thrilled to have my car running good again.

Listed

my sensor was only down to like 2.98 at 18 in. Hg does that indicate that it is faulty or what? BTW, I have the 3800 BS

Thaniel

If it doesn't read 3.5V with key on engine not running and then 2.5-3.5 V with 3.9" Hg. Then I would say it is bad.

Keep in mind these readings are from the 87 N/A factory service manual. If you have a different car check those specs.

Does the sensor hold vac? I would expect a lower voltage with 18in HG.

rexman13b

iTrader: (7)

Ok, I had this same problem on my 87 T11, and just fixed it 2 days ago. It was the solenoid resistor, I tested it like the FSM said and it wasn't within spec so I replaced it, no more hesitation. To check it take an ohmeter, take the plug, there are 5 metal prongs you can see once you disconnect it. The 1 prong in the middle, take the red lead from the ohmeter then touch the one prong in the middle. Then touch other lead (black) to each other metal prong one at a time while the red lead remains on the middle prong each time. FSM says 5-7 ohms. Might be kohms, don't remember so you might have to switch your multitester to 20 kohms to test them. One of the prongs on my resistor read 0 that lead to the secondary injectors and that caused the hesitation. So try that let me know how it goes. By the way the solenoid resistor is the silver box mounted on the front of the right shock tower below the airbox, which you will have to remove to see it.

Angel Guard Racing Team

My car died on me yesterday. I removed the upper intake manifold and with the ignition on I checked for voltage on the injectors and there was none!!!!!! I checked a few seconds later and there was voltage. Weird.... Also if I press the gas gently on neutral at about 5000 RPM You can feel a "Click" and the car just drops in RPM's... Could it be that the secondaries are not opening? My pressure sensor is disconnected from the vaccum line and my TPS does not wanna turn any lights on no matter how many times I turn the screw after warming the engine and follow all of the procedures...
In other words HELP!!!!!!!!!! I'm mostly interested in the injector stuff...

Angel Guard Racing Team

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Vroomaster

Ok HAILERS, I finally tapped into my secondary injector wires and got the following reading: at Idle/low RPM .032volts, while locked/hesitating it dropped quickly to .018 volts. So, There must be a short? or is it the ECU itself do you think?

Thanks!

Vroomaster

bump

Vroomaster

Update on my hesitation/non-function of secondaries. I just tested both front & rear for continuity and we have continuity both ways-direct & through selenoid(?).

Next, I will be hooking up a direct line of my own from the ecu to the secondaries to see if it might be a short or something. Is there another way to test for a short?

Blowtus

von, measure the voltage at the throttle sensor pin on the ecu while driving. I've recently resolved a bucking issue, the tps was buggered... this will check it while driving. If the voltage drops wildly when the car starts bucking then this is the problem... Haven't read every post in this thread in depth, sorry if I'm being irrelevent

Charlie

RrtyRckt

O man, I have the 3800 rpm hesitation problem and I can NOT figure it out. I know this who forum is practically dedicated to figuring it out, but I can't gather the right info to get rid of this damn problem. Could someone PLEASE pm me with the answere to my 3800 rmp hesitation problem.

THANK YOU

von

BLOWTUS- ok thnx. I wasnt ever going to look in this thread again. Luckily I did. ANyways I still get that jerk ever second at cruise so I will try this or just put in working used tps and see if that fixes it. I will reply back here later

Rrtyrckt- its either your injectors or grounds. Hope someone can give you step by step. I ahve that 3800 rpm hesitation now even worse than before. I ran my gas tank dry twice. REALLY DRY. I didnt know it because my gauge read a little diff than usual. But like I said. KNow the hesitaion is more profound and quite anyoning. I will buy two new primairies. DO NOT GET USED ONES. I have and got ripped off.