PAFirefighter11 Posted September 21, 2009 Report Share Posted September 21, 2009 PCM, TPS, Crank Position Sensor, MAF, ECU, anything else? The car is running beautifully at idle and up to 2500 RPM during slow increase of the throttle. However, if somewhat stomped, it can rev upwards of 4000 RPM, but quickly drops back under 2500. I have searched for replacement sensors and located most of the ones I will need, but they are quite expensive. Ideally, I am trying to find a local Starquest owner who will let me "borrow/test" sensors and the PCM with him/her right next to me, so I can resolve this issue. Link to comment Share on other sites More sharing options...
Edde Posted September 22, 2009 Report Share Posted September 22, 2009 (edited) Are we talking about under load or free revving? No crank sensor. ECU's are rarely bad. Secondary injectors (both injectors) are frequent culprits on running issues. Fuel delivery is a HUGE issue when the pumps and filters get old. Toss an ohm meter on them - look for 3.5 ohms. There's a million threads on testing injectors but cleaning them if they work is best sent out. Might find what you need here: http://starquest.i-x...6c21194fb05d761 Do be careful spending on parts you probably do NOT need. Test the TPS for sweep and output, that kind of thing. They're probably $200 these days new. An ignitor can be had for $20 here but dealer sold for $400 like 10 years ago. Edited September 22, 2009 by Edde Link to comment Share on other sites More sharing options...
Technology Posted September 22, 2009 Report Share Posted September 22, 2009 It's either a bad injector or mass air sensor or the wastegate is unplugged. And it's AJUSA, not Agusta. Link to comment Share on other sites More sharing options...
Indiana Posted September 22, 2009 Report Share Posted September 22, 2009 The distributor times the ignition event mechanically and sends a signal to the ignitor to fire the coil. The rpms are raised from this but that's because the throttle opened and allowed in more air. The injectors are fired based off rpms and how much from other sensors. TPS is only for throttle enrichment for throttle-up or fuel cut on decel. TPS quick movement causes secondary injector to come in. TPS isn't causing your issue. High rpms and/or boost also makes the secondary come in. Sounds like dirty clip on the secondary or the secondary is just dirty and or the primary too. 02 sensor can't do that much and it can't correct for dirty injectors. Fuel dispensed improperly won't burn as efficiently. Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 22, 2009 Author Report Share Posted September 22, 2009 Are we talking about under load or free revving? No crank sensor. ECU's are rarely bad. Secondary injectors (both injectors) are frequent culprits on running issues. Fuel delivery is a HUGE issue when the pumps and filters get old. Toss an ohm meter on them - look for 3.5 ohms. There's a million threads on testing injectors but cleaning them if they work is best sent out. Might find what you need here: http://starquest.i-x...6c21194fb05d761 Do be careful spending on parts you probably do NOT need. Test the TPS for sweep and output, that kind of thing. They're probably $200 these days new. An ignitor can be had for $20 here but dealer sold for $400 like 10 years ago. This "2500 redline" is both free idle and under load. I did a visual check of the spray. The primary injector looked to spray fine. Plenty of fuel on the TB flap. When hitting the gas hard it would kind of burp/backfire with the TB exposed while we were watching the injectors spray. TPS sweep looked fine. It was a smooth movement. This is from my mechanic buddy (13 years as a Chrysler Mechanic) who looked at the car on Sunday:Yes, the throttle bodies butterfly can be closed or all the way open. ya , the tps gives a voltage reading to the PCM<power control unit> between .10v to 0.50v at closed throttle and at W.O.T< wide open throttle>it can get to 4.5v or above .Yours was .14v on the one wire and 5.60v on the other your ground was good too.I dont think its the tps, but i'm not sure, i think pcm you know, or a boost conrol switch, sensor. It's either a bad injector or mass air sensor or the wastegate is unplugged. And it's AJUSA, not Agusta. I will check the wastegate tonight. Just listing parts that the prev. owner listed to me lol. The distributor times the ignition event mechanically and sends a signal to the ignitor to fire the coil. The rpms are raised from this but that's because the throttle opened and allowed in more air. The injectors are fired based off rpms and how much from other sensors. TPS is only for throttle enrichment for throttle-up or fuel cut on decel. TPS quick movement causes secondary injector to come in. TPS isn't causing your issue. High rpms and/or boost also makes the secondary come in. Sounds like dirty clip on the secondary or the secondary is just dirty and or the primary too. 02 sensor can't do that much and it can't correct for dirty injectors. Fuel dispensed improperly won't burn as efficiently. Alright, I'll look into these guys again. I did all that testing months ago and I thought all was well, but I shall try to confirm again. Thank you! Link to comment Share on other sites More sharing options...
Indiana Posted September 22, 2009 Report Share Posted September 22, 2009 OVCP has to be on to rev the motor. Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 22, 2009 Author Report Share Posted September 22, 2009 OVCP has to be on to rev the motor. I figured that out after it backfired in my face haha ;-) Link to comment Share on other sites More sharing options...
Technology Posted September 22, 2009 Report Share Posted September 22, 2009 Just so we're all on the same page, a backfire is when the fuel in the intake manifold burns and smoke and fire comes backward through the throttle body. It sounds like that happened to you, which would make me think you have a timing problem. Maybe the plug wires are on wrong? it's 1-3-4-2 starting at the top left if you're looking at the distributor straight on. And you'll need a timing light to set it at 10 degrees before tdc at idle. Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 22, 2009 Author Report Share Posted September 22, 2009 (edited) Is there a limp (or safe) mode on these cars if something is not reading properly at the ECU? Basically my rev limiter is at 2500, idles great, timing is great, TPS is good. Edited September 22, 2009 by PAFirefighter11 Link to comment Share on other sites More sharing options...
mikec Posted September 23, 2009 Report Share Posted September 23, 2009 StarQuest ECUs are about as "dumb" as you can find on a computerized car. The ECU has no built-in RPM limits (you can mash the gas in neutral and rev up until parts fly through the block), it doesn't monitor engine knock (the ignition module does that, it doesn't bother telling the ECU if knock is present), and it barely monitors the various engine sensors to trigger error codes. To trigger an error code, a sensor has to be really screwed up typically. Some of the sensors are checked for errors only while the engine idles for example. On 87-later cars, the engine starts, idles, and putt-putts at low RPMs on only one of the two injectors. When RPMs get to 2500ish, the ECU "backs off" on that injector and starts adding the second injector. If the second injector isn't working, the car "hits a wall" because the ECU has backed off on the first (primary) injector. Test your blue/green secondary (87-later cars only...): unplug the electrical connectors on the two injectors. Move the one from the black injector to the blue/green one. Try to start & idle. If it'll start & idle (it'll be a lumpy over-rich idle) then the injector is basically functional. It may not be 100% good, but at least it's in the ballpark. The bug is either in the ballast resistor that supplies +12volts to the injectors, the wiring to/from the injector, or the ECU driver for the secondary injector is shot. Unplug the connectors and leave them unplugged for the next tests:With the key ON, look for +12volts on one wire of each injector electrical connector (aka "clip"). This is the +12volts from the ballast resistors. If only the primary has +12volts, remove the air filter box (turn the key OFF first!) and you'll see a silver box screwed to the bodywork between the air filter and headlight: that's the ballast. It's two resistors in one metal wrapper. +12volts in on one wire, +12volts out on 2 separate wires to each injector. Verify that +12volts (key ON again) on all three wires. If only 2 have power, the ballast is junk. If all 3 have power, the wiring from the ballast to the secondary injector is junk. If both injector connectors had +12volts on them, then the wiring from the connectors to the ECU is junk or the ECU is bad. mike c. Link to comment Share on other sites More sharing options...
89Steve Posted September 23, 2009 Report Share Posted September 23, 2009 PCM, TPS, Crank Position Sensor, MAF, ECU, anything else? The car is running beautifully at idle and up to 2500 RPM during slow increase of the throttle. However, if somewhat stomped, it can rev upwards of 4000 RPM, but quickly drops back under 2500. I have searched for replacement sensors and located most of the ones I will need, but they are quite expensive. Ideally, I am trying to find a local Starquest owner who will let me "borrow/test" sensors and the PCM with him/her right next to me, so I can resolve this issue. Im about 20 mins away from west chester. If you still dont have the issue figured out I can try to being my quest up on friday or saturday to see if I can help you out. Shoot me a PM with your number if you want. -Steve Link to comment Share on other sites More sharing options...
Dcrasta Posted September 23, 2009 Report Share Posted September 23, 2009 Based on the information you supplied I would say check the secondary injector and its clip/wiring.You can test the injector by switching the clip from the primary over to the secondary injector. The car will start (but not idle) on the secondary injector. Just do it briefly to test if the injector is firing . If it is then its likely your injector clip Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 24, 2009 Author Report Share Posted September 24, 2009 Thanks guys, I swear I checked the injectors before and all was well, but I'll double check if I get a moment tonight or Saturday night. Steve: That would absolutely rock! At least at that point I'd be able to narrow it down to a certain sensor or something. It'd be nice to see the engine bays side-by-side as well. There are a few things in mine that I'm unsure are correct or not. It would be much appreciated! My first free moment this weekend is going to be Saturday night, probably after 9pm is when I'll be home. The car is at my buddies house (whom I purchased it from) in Chadds Ford (Closer to DE), just off of 100/Creek Road and Route 202 - easy to find from DE. I'll PM you my #. My phone blows and I don't always have signal, so I typically have to text (it sucks). I need a new phone too. "The things you own, own you" ... fun! Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 25, 2009 Author Report Share Posted September 25, 2009 (edited) Both injectors are good. Car runs with either hooked up. Checking voltage when I get a free moment.. may not be 'til next week. Edited September 25, 2009 by PAFirefighter11 Link to comment Share on other sites More sharing options...
Indiana Posted September 25, 2009 Report Share Posted September 25, 2009 Both injectors are good. Car runs with either hooked up. Checking voltage when I get a free moment.. may not be 'til next week.This may be the problem. The car will run with only the primary plugged in to the correct clip. If you did this with the other clip removed then reconnected it nothing should change as at idle that clip isn't doing anything. If you can the put the clip from the primary on to the secondary injector the car may start but VERY quickly FLOOD as that injector dispenses at least twice the fuel as the primary. This should tell you what I said before those injectors are so dirty it barely sprays fuel and that wrong amount . Have them cleaned you are wasting your time and this is why the motor won't rev up. Link to comment Share on other sites More sharing options...
PAFirefighter11 Posted September 25, 2009 Author Report Share Posted September 25, 2009 Gotcha, thanks Indiana! Link to comment Share on other sites More sharing options...
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