RedSpaceship Posted November 12, 2009 Report Share Posted November 12, 2009 Hey guys, first and foremost, great community you guys have built here. I am a new owner of a nice looking not so nice running 87 with apparantly a 88 computer and harness. Short story is the car ran and somewhat went into boost (with a pop half way through) when i got it and now it will not transition into boost at all. Its like there is a wall it hits when you try to take it past 2-3k RPM. After much research on this site as well as a few vendor sites most seem to point to the secondary injector not firing. My initial test to see if the secondary is dead was to swap the inj plugs and see if she starts up still. That she does ... So my question becomes how do i test that the secondary injector circuit is actually doing its job when boost is supposed to kick in and providing a pulse to the injector. So far i changed the spark plugs and gapped them properly, rotor and cap with a high quality replacement, plug wires, and checked the timing to make sure it is to spec. I did not check the timing vac or rpm advance as it does not feel ignition related due to the sudden drop of power to a point where acceleration is beyond its ability. Doing all these maintenance items has not helped any... Other items i am considering are: Fuel pressure ... have a test gauge on the way.MAF ... looks rather beat up but doubt it would idle as well as it does with it dead. Shoot me your ideas guys ! much appreciated ! I will be doing research in the mean time .. treasure trove of info here just gotta search. Link to comment Share on other sites More sharing options...
ucw458 Posted November 13, 2009 Report Share Posted November 13, 2009 Does it do it under load? If so will it stop revving at around the same rpm in all gears. If it does check for a plugged exhaust. Link to comment Share on other sites More sharing options...
boostdquest89 Posted November 13, 2009 Report Share Posted November 13, 2009 If it ran when u switched your inj. clips it isnt your secondary! Might wanna check your vac. advance!Chad- Link to comment Share on other sites More sharing options...
Vnomous1 Posted November 13, 2009 Report Share Posted November 13, 2009 Hey guys, first and foremost, great community you guys have built here. I am a new owner of a nice looking not so nice running 87 with apparantly a 88 computer and harness. Short story is the car ran and somewhat went into boost (with a pop half way through) when i got it and now it will not transition into boost at all. Its like there is a wall it hits when you try to take it past 2-3k RPM. After much research on this site as well as a few vendor sites most seem to point to the secondary injector not firing. My initial test to see if the secondary is dead was to swap the inj plugs and see if she starts up still. That she does ... So my question becomes how do i test that the secondary injector circuit is actually doing its job when boost is supposed to kick in and providing a pulse to the injector. So far i changed the spark plugs and gapped them properly, rotor and cap with a high quality replacement, plug wires, and checked the timing to make sure it is to spec. I did not check the timing vac or rpm advance as it does not feel ignition related due to the sudden drop of power to a point where acceleration is beyond its ability. Doing all these maintenance items has not helped any... Other items i am considering are: Fuel pressure ... have a test gauge on the way.MAF ... looks rather beat up but doubt it would idle as well as it does with it dead. Shoot me your ideas guys ! much appreciated ! I will be doing research in the mean time .. treasure trove of info here just gotta search. Like the other post mention, does the car have it's original exhaust system? If it does, likely to have have a clogged cat coverter(s) unless you know for a fact they has been gutted or replaced. If the exhaust is OK, consider replacing the vacuum advance. They go bad and the symptoms you descibe are consistent with a bad one. Also consider the fuel injector clips, are they the original ones? if so, it is likely they will need to be replaced as they get worn, brittle and corroded. Keep the fuel system in mind too, regarding fuel filters, trash in the tank, and fuel pump. You will, like many of us, find that owning one of these cars after they have been neglected with little to no maintenance, will require you to do some repairing, AND preventive maintenance to keep them going and running correctly. If you are not prepared to personally "bend some wrenches", things can get really expensive fast. So, do yourself a favor, and ensure your electrical connections are clean, tight and dry, (from your battery cables to serviceable fuses) the grounds are clean and not corroded, the cooling system is serviced and operating properly (VERY IMPORTANT) and your ignition system (from the distributer ignition module to the last spark plug) is serviceable) Link to comment Share on other sites More sharing options...
RedSpaceship Posted November 13, 2009 Author Report Share Posted November 13, 2009 Good suggestions guys.. Yes it acts the same under load and otherwise. You can try to build boost in any gear and it just falls flat at 3k every time. No on the exhaust being clogged as its a 3in turbo-back with no cat. I will check the vac advance and report on it ... Inj plugs are what i suspected and redid them with new Bosch EV1's first thing, no change in situation from the grossly coroded stock plugs... Worst case... if i cannot get it running with the system as is i'll tear into it and drop a MS2 + EDIS and get rid of the stock computer and distributor .. i am all too familiar with that kind of setup and find it very easy to troubleshoot compared to a system that gives little to no feedback like the stock stuff in its current state of disrepair. Got the garage, tools, and experience but no time Anyhow, anyone have ideas for testing secondary fuel inj circuit to make sure it is doing its job ... hoping the inj driver in the ECU did not fry. Common thing on cars i've had in the past. Link to comment Share on other sites More sharing options...
RedSpaceship Posted November 13, 2009 Author Report Share Posted November 13, 2009 clips it isnt your secondary! Might wanna check your vac. advance!Chad- agreed... def not the sec inj but still may be a faulty sec inj circuit or driver. checking the vac advance ASAP. Link to comment Share on other sites More sharing options...
Zero Posted November 14, 2009 Report Share Posted November 14, 2009 If it ran when u switched your inj. clips it isnt your secondary! Might wanna check your vac. advance!Chad- Having a similar problem. When you switch inj clips, is it supposed to run smoothly, or just run? My car started up fine, but idled like cr*p. Like 2 of 4 cylinders were missing. Link to comment Share on other sites More sharing options...
Indiana Posted November 14, 2009 Report Share Posted November 14, 2009 (edited) Secondary injector dispenses twice the volume of fuel at idle compared to a primary can you say flooded and fouled plugs? No, your car with a stock cam will not idle with a secondary connected to the primary clip for very long. This all points back to a bad vacuum advance unit. Read in the link below what the Vacuum Unit does and you'll understand how a bad one, and I'd guess there are no original installed ones still working at this point and many bad and leak so they can't retard timing, can cause your described issue. If anyone sees errors in this let me know or thinks I should add to it. http://www.b2600turbo.com/distributorvacuum_advance_unit.htm Edited November 14, 2009 by Indiana Link to comment Share on other sites More sharing options...
mikec Posted November 14, 2009 Report Share Posted November 14, 2009 Quick test of secondary injector on 87-later StarQuests:1: start the engine and let it warm up.2: tranny in neutral, parking brake set, engine idling: stomp on the gas pedal. If the engine stumbles badly or stalls, the secondary injector circuit is crap. If the engine smoothly starts to rev up then the secondary is trying to function; other issues are limiting it. Ever drive a carb engine with a busted "accelerator pump?" If you have, you know you have to "baby" the throttle to make the vehicle accelerate; it'll stumble/buck/stall if you mash the gas. On the 87-later cars, the ECU uses the secondary injector as an "accelerator pump" during low RPM "mash the gas" accelerations. Things that lead to a bad secondary circuit:* Injector "ballast resistor" is bad. This is really 2 resistors in one case, one +12volt input wire and 2 output wires (one output for each injector). It's mounted to the bodywork bulkhead between the air filter and headlight, it's a silver rectangular prism. With the ignition key ON, disconnect the electrical leads to both injectors. Use a voltmeter to measure from the battery "-" post to the injector connectors. Each injector should have +12volts on one of the two wires if the ballast is working. The other wire is grounded by the ECU to "fire" the injector. * Wire harness has failed. More commonly the "injector clips" (the electrical connectors at the injectors) have corroded and are making crappy connections. Cars that had a windshield water leak will have corroded connections at the ECU - especially the pre-88 models since those cars had the connectors on TOP of the ECU case... right where the bodywork "A" pillar dumps water. * Rare: ECU output driver has blown. Need a replacement ECU in this case. * Bad secondary injector. Quick test: swap the electrical connectors between the two injectors. Try to start the engine. If it'll start and idle (it'll be a lumpy/rich idle) the secondary injector itself is basically functional. Put the electrical connections back to original. mike c. Link to comment Share on other sites More sharing options...
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