87chrycon Posted September 7, 2008 Report Share Posted September 7, 2008 (edited) Here is a brief description of what I have done.....87 Quest with 88 ECU/knock box installed (soldered in). 3" exhaust from turbo back with new o2 sensor (no cats). New exhaust/intake manifold gaskets installed as well. TB rebuilt and all vacuum lines removed and capped except FPR, Vac Advance, and HVAC--new vaccum hoses to these. New correct injector clips soldered in with injectors which OHM out correctly. TPS/ISC reset has been performed exactly as directed 3x. 3 different TPS's installed pass the 2 tests (sweep test and voltage test) that I have located in the search function. Disconnected FPR vacuum feed and it did not change issues below. I am currently using 92 octane fuel and have not been able to check the timing. Here are the codes my computer has stored on it. 1.--o2 sensor (when car is warm), 5.--TPS, and 6.--ISC....... So if the ISC is bad will this prevent me from actually being able to set the TPS correctly? Will a faulty ISC affect the o2 sensor? (I did not think that it would but asking people who know) Car idles very well but does go up and down about 100 rpms (800-900rpm) at times when idling. I am having a very annoying issue with major hesitation when under load at about 4K. Car will feel like it is loading up on fuel and bog down until I let off the accelerator for a moment. Will not boost past 7lbs on the stock dash gauge without these issues. Runs good through the power band without using wide open throttle but still has the hesitation at around 4.5K even when not at WOT. Last night on the interstate I also noticed that when I shift from 3rd to 4th or 4th to 5th it will give me a quick "buck"/miss at about 3K--4K under normal cruising acceleration--feels like fuel--not mechanical in nature. Car will rev to 5500 when not under load without any problems. Runs very choppy when starting cold and car has sat all night with temps below 50*--improves with coolant temp increase--found this to be the case this morning when I drove to the gas station. Car is getting very good mileage if I use cruise control and stay out of the boost--drove to Des Moines and back (290 miles) on a full tank of gas. I did notice the hesitation when cruise control used the boost on a steep hill.... I have a spare set of injectors and 2 spare ISC motors to swap but would like to see if anyone knows what may be going on here first. I am going to disconnect neg. battery terminal (clear ECU code memory) today and see if the codes reappear as I have been doing a lot of work on this thing the past 2 weeks. I believe that the ISC is the problem but would like to here from others that have already addressed this........TIA for any replies. Edited September 7, 2008 by 87chrycon Link to comment Share on other sites More sharing options...
Richie_Rich Posted September 7, 2008 Report Share Posted September 7, 2008 Part of the TPS/ISC reset for the 87-89's is checking the voltage and the "Zip" sound at the ISC. Did you do that? Do you have a fuel pressure gauge where you can keep an eye on the pressure while driving? I recently had issues with my car and it turned out to be the primary injector allowing too much fuel. It wasn't leaking, it just appears to not be able to turn on and off the fuel quickly enough so it seems to never fully close. Since you have made a series of modifications, which ones did you do where the car ran fine after making them? ECU swaps along with wire modifications are subject to errors and should be only done on a car that runs good in the first place and then checked afterward. A friend of mine did a whole bunch of modifications to his car and it took him a long time to figure out what his problem was because he had so many things to try and diagnose. Link to comment Share on other sites More sharing options...
Dcrasta Posted September 7, 2008 Report Share Posted September 7, 2008 ISC has a nose switch that has to turn off on decel. I would replace the parts throwing codes. another thing to try. disconnect the ECU use a probe and probe the wires in the tps and isc out. If you disconnect the ecu at the kick panel, and make yourself some 'test probes' (alligator clips ) to ground the wires that connect to the sensors, you can test the harness for any shorts . (if you cant get a signal from the sensor to the ecu you will throw a code. _) You may have some damaged insulation (I did) causing a crappy connection to the sensor. Link to comment Share on other sites More sharing options...
Technology Posted September 7, 2008 Report Share Posted September 7, 2008 Sounds like it could be a bad mass air sensor. Link to comment Share on other sites More sharing options...
87chrycon Posted September 7, 2008 Author Report Share Posted September 7, 2008 (edited) Richie---I did not have the 87 car running properly when I parted out the 88 tsi with a blown engine but the parts that I swapped were all funcitoning properly.. ISC voltage and "zip" are up to par. My soldering is near bulletproof as I have been doing it for 25 years--not to say I am perfect but I have never had a problem before. No way to check fuel pressures as of now but that may be coming soon. The driveability issues are the same as they were when I began tinkering so I do not believe it is anything that I have added or changed. Technology---No code for the MAS so I am not going to mess with it yet. Dcrasta---Where do i find the wiring diagram to know which wires out of the ECU go to which sensors in the engine bay?? I have an 87 FSM and a 89 FSM so if you have the page please elaborate. After disconnecting battery I am still geting the TPS error (#5) and will try another reset/calibration on that today. The other codes are gone and that is a relief. I did have some difficulty tightening the TPS and holding it at .50 volts last time as I have allen head bolts on the TPS fastening points--I will get my son to tighten it while I hold it this time so I can be sure that it is tightened with proper voltage...... Edited September 7, 2008 by 87chrycon Link to comment Share on other sites More sharing options...
mikec Posted September 7, 2008 Report Share Posted September 7, 2008 The "ECI System Circuit" schematics exist in the fuel system chapter of the main volume of the FSM and are duplicated in the electrical volume as well. Look at pages 14-41 (or so) of the main volume or 8-48 (or so) of the electrical volume. Those are the pages in the 88 Conquest manuals that you can download from several places in PDF format. The TPS error code is set by the ECU if the TPS output voltage drops below 0.2 volts or is above 4 volts while the idle/nose switch of the ISC assembly is closed (engine at idle). Since 0.5 is the normal "idle" TPS reading, getting down to only 0.2 volts generally means: * TPS has a dead spot in it * You're not setting the TPS adjustment on a warmed-up engine with the right idle speeds or something - and missing it by a LOT. Pretty rare. * Wiring to/from the TPS and ECU is damaged. * The +5 volt "sensor power" output from the ECU is intermittent. That screws up the output of most engine sensors to the ECU - they share this power feed. Some other flakey sensor might be shorting out for a moment, shorting this +5 volt line triggering TPS error codes. Look at the wires going to ALL engine sensors, especially the wires going to the coolant temp sensor attached to the intake manifold near the oil dipstick. Or just unplug the wires to that sensor and stuff a 270 ohm resistor into the wiring harness connector... this simulates a warmed-up engine. If your situation improves, you've got a bad ECU coolant temp sensor - very common. Sometimes they OPEN completely at certain temps (and outside that temp they test OK) and sometimes they short out at certain temps... very annoying. Do an ISC "sweep test" - it's simple. You'll need a good ohmmeter (just like you used to test the TPS) and 4 "AA" batteries in a small plastic holder. Do NOT use anything more than 6volts of power - and certainly don't use a car battery unless you want to make sure your ISC is bad by blowing it to smithereens. There are two connectors coming from the ISC/MPS assembly: 1 has wires clearly going to the black-plastic/rubber covered motor. That's the actual ISC motor and motor connector. You'll connect the batteries to the two wires going to the motor. 1 has wires going "somewhere underneath the bracket" - that's the MPS (Motor Position Sensor). You'll hook your ohmmeter to 2 of the wires on this connector. Pick the two connector prongs/wires closer to the index pin (locking tab/ear) on the connector. Now connect the batteries to the motor wires. You should see/hear the motor running and you'll see the rubber bellows either extend or contract depending on the battery polarity. Watch the ohmmeter... it should SMOOTHLY change in sync with the motion of the bellows. When the bellows stops, reverse the batteries. Repeat this several times, watching the ohmmeter. And make sure the bellows extension/retraction is nice and smooth. Any jerkiness means the gears inside the assembly are damaged, the grease has dried out, etc. Those are easily fixed. Sometimes though a small metal washer plate deep inside the mechanism (down by the bellows) gets bent; this happens if something overdrives the motor (like hooking a car battery to the motor...) or if the throttle linkage in the car is slammed around by tools or whatever. This is harder to fix. One last test: disconnect the ohmmeter and hook it to the 3rd wire of the motor connector - the one we've ignored so far. Connect the other ohmmeter lead to the metal casing of the ISC/MPS assembly. You should be reading infinite ohms/open circuit. Press the very tip of the bellows - that small metal "button" which is the idle/nose switch. The resistance should read zero ohms now. Press and release the switch several times. A flakey idle/nose switch leads to lousy engine idling and inconsistent idle RPMs. mike c. Link to comment Share on other sites More sharing options...
mikec Posted September 7, 2008 Report Share Posted September 7, 2008 Oh, one other thing: examine the connectors that plug into the ECU itself. On the 87 and earlier cars the ECU connectors catch any water from a leaking windshield... leading to corrosion and lousy connections to the ECU. What happens is water leaks around the windshield collects inside the roof... the water runs down the "A" pillars (the bodywork on either side of the windshield) and gets dumped onto the ECU (passenger side) and relay box (driver side). If you see dirt/water streaks on the bodywork behind or above the ECU get your windshield re-sealed. Look at the driver side too... pull the carpet back and look for signs of water. mike c. Link to comment Share on other sites More sharing options...
Dcrasta Posted September 8, 2008 Report Share Posted September 8, 2008 also the TPS hooks onto the lever from the TB. IF its not hooked on the right location that could 'throw' the wrong value. The pinout for the CPU has been posted in the FAQ section. Try searching for it. Link to comment Share on other sites More sharing options...
87chrycon Posted September 12, 2008 Author Report Share Posted September 12, 2008 swapped out the secondary injector for one I saved from a parts car and that solved the problem. still getting TPS code (#5) but nothing noticeable while driving. Sure is nice to boost again.......thanks for all the input guys..... Link to comment Share on other sites More sharing options...
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