yamahlr Posted May 7, 2015 Report Share Posted May 7, 2015 Have a mint 35K all original 87 Conquest, I'm second owner (couple of you guys have seen it). It is all stock. Needed fuel pump replacement, new fuel screen,new fuel filter (by engine), injectors cleaned. Car runs very well at idle, while on road after a few minutes of driving, as the rpms build, the car is feels like it's running out of fuel. As you get off the gas, responds better. This condition gets worse the longer you drive. It doesn't exhibit this when just coming out of the garage (engine cold, but warm ambient air temp. Anybody have any ideas on this. The check engine light is not on and the car idles well, all fans /gauges show fine. Very frustrated as is my mechanic who was trained in these cars @ Chrysler back in the day. Been going on a month now. Link to comment Share on other sites More sharing options...
tsi_tom Posted May 7, 2015 Report Share Posted May 7, 2015 (edited) Who cleaned the injectors? Did you change the injector clips? Edited May 7, 2015 by tsi_tom Link to comment Share on other sites More sharing options...
mikec Posted May 7, 2015 Report Share Posted May 7, 2015 What check engine light? There isn't one on the dash/instrument panel. There is a test port in the top of the glove box where you can connect a voltmeter or a 12volt LED to check/monitor ECU error codes. There are only a few error codes though - not much help. And the symptoms you've described won't trigger ECU error codes anyways. Possibilities:* Bad fuel pump. Some aftermarket ones are pretty crappy. Old/dying fuel pumps tend to work okay when physically cold and then crap out as they get hotter... thermal expansion causes spinning parts to rub and slow down until the pump totally jams. * lousy wiring in the fuel pump circuit including a too-old "ECI" fusible link. Or a poor ground at the fuel pump itself. Both deny the fuel pump proper working electical energy. * There are small filters at the fuel pump inlet and at the end of the fuel pick-up tube. These could be clogged - often happens on cars that sit for a while and get rust on the fuel tank inner walls from the trapped humidity. * gas cap vent function busted so a big vacuum builds up in the gas tank as the fuel pump sucks out fuel... eventually the pump can't overcome the vacuum and the fuel flow rate drops. If driving the car with the gas cap removed works better, get a new gas cap. There is no "gas cap" ECU error code either, nor a "evaporative emissions system failure" error code on StarQuests. * Any chance the car is actually running over-rich instead of loosing fuel? Issues with the fuel pressure regulator or a blocked fuel return hose lead to excessive fuel going through the injectors. At high power the over-rich can lead to a bucking sensation and a general lack of power. The coolant temp sensor used by the ECU (different sensor from the one that drives the dash temp gauge) is a common failure point; when it goes bad the ECU thinks the engine is stone cold and runs it over-rich. Usually there is a bucking/hesitation when trying to accelerate hard but the engine will run okay when babied if this sensor fails. It's the 2-prong sensor in the intake manifold, next to the oil dipstick, with a squarish connector. The sensor is mounted vertically with the prongs pointing upwards. * weak spark can cause these symptoms, especially if it is from a dying ignition coil. Like the fuel pump, dying ignition coils often work okay when cold and get progressively weaker as they heat up. Incorrect spark plugs or too-large plug gaps can also cause problems. StarQuests like old-style basic plugs... not the expensive platinum plugs or other long-life ideas. Many of those fancy and expensive plugs can't take the abuse of a turbo engine anyway. * wrong injectors... lots of different injector flow rates were used on Mitsu cars over the years. The 87s use a low-flow-rate "primary" injector with a black plastic band, and a higher flowing "secondary" injector with a blue or green band. Unfortunately a lot of other Mitsu injectors have the black color... and Mitsu Japan was shipping incorrect flow rate injectors as spares for many years - a situation they never corrected. Those medium-flow black banded injectors won't work in 87-later StarQuests. If you look carefully at the injectors you should see faint letter+number codes stamped into them just below the plastic ring. The black banded injector should have an "L" letter, the blue/green one should be an "M" label. Ignore the numbers, they don't matter... just the letters. Also, while the engine is idling, unplug the connector on the blue/green banded injector. The engine should continue to idle just fine; if it dies the injector connectors are backwards. Only the black banded primary is used at engine idle. * Incorrect method used to set ignition timing. StarQuests have a simple electronic ignition system; timing is not controlled by the main ECU. The ignition module does get 2 signals from the ECU that slightly modify how it works... but the ignition system can operate even with the ECU unplugged - it's that independent of the ECU. One of those 2 signals is a signal sent by the ECU when the engine is stone-cold or the ECU thinks the vehicle is operating at a high altitude; when present this signal makes the ignition module advance the timing 5 degrees beyond what the centrifugal weights and vacuum advancer mechanism call for. If somebody sets/checks ignition timing on a cold engine, or when the engine is in fact at high altitude, the timing probably got set to the 10 deg BTDC service manual specification when it should have been set to around 15 deg BTDC thanks to the extra 5 degrees of advance. There is a 2-wire connector hanging from the wire bundle between the air filter and fender... unplug the protective cap on this puppy and jumper the wires together. This forces the ignition system to "warmed-up engine at low altitudes" removing the extra 5 deg timing advance - now you can properly set the ignition timing to 10 deg BTDC. That's the correct procedure - using that jumper first. StarQuests with incorrect ignition timing - especially retarded a few degrees - have significant power loss. A car with the timing tuned/set while the engine was cold will end up with only 5 deg BTDC once a little heat is in the engine and will be a total dog. * A partially plugged exhaust from old/damaged catalytic converters will slowly choke off the engine; it'll happen faster at higher power settings. Take the car for a drive without "mashing the gas" - just around town at 40 to 50 MPH until you feel the power loss is significant. Pull over (engine still running) and quickly pop the hood. Look at the exhaust end of the turbo. If it's glowing at all then you can bet there is an exhaust blockage. Usually the "pre-cat" (first catalytic converter --> the one bolted to the turbo) plugs first. If the vehicle ever had a "blown turbo" or other major issue then oil got into the pre-cat and that's a pretty fast way to kill it. Has the mechanic connected a fuel pressure gauge to the engine? That will tell you if the issue is fuel delivery (wiring, fuel pump, blocked passages, gas cap, etc.) or someting in the engine itself (ignition timing, plugged exhaust, etc.) There is an allen-head plug at the very top/rear of the throttle body where a fitting can be inserted (instead of using the "special service tool" funky block shown in Mitsu's service manuals). Use a couple washers between the driver side hood hinge and hood to lift that corner of the hood for the gauge's hose and you can tape the gauge to the wipers will you go for a test drive. You should see 36 to 38 psi at idle or while driving; the pressure should increase in sync with turbo boost pressure (i.e. 41 to 43 psi when the turbo is creating 5 psi boost). If the pressure drops off while you drive then it's a fuel delivery issue. mike c. Link to comment Share on other sites More sharing options...
JohnnyWadd Posted May 7, 2015 Report Share Posted May 7, 2015 (edited) Check engine light wont help but you can check codes. http://www.starquest...30614&hl=reader Your issue sounds like a bad ECT sensor. Needs to be at 300 ohm when hot. If its bad you get drivability issues when warm. Mechanic should be checking fuel pressure while running and also squeeze off the return line to see how much psi it makes. While your doing that pop off the ovcp and check those injectors for leaks. Also , you may have got the injector clips mismatched. Make sure the primary and secondary injectors are plugged to the right clips. You can test the firing with a noid light or an LED like in the write up I linked above. Next issue this sounds alot like it bad vacuum advance or injector clips are dirty and not firing the secondary injector under boost Sounds like it ran good and then after the pump work it has this issue? Show your mechanic this free online service manual www.starquestgarage.com Edited May 7, 2015 by JohnnyWadd Link to comment Share on other sites More sharing options...
89StarQuestNYC Posted May 7, 2015 Report Share Posted May 7, 2015 When you say New Fuel Screen? Do you speak of Filter on pick-up tube in Fuel tank? Or very small cone shape filter on inlet of Factory Fuel pump? I know I ran into issues when under load when reinstalling cone type filter after fuel pump replacement. Link to comment Share on other sites More sharing options...
yamahlr Posted May 8, 2015 Author Report Share Posted May 8, 2015 WOW! Thanks for all these replys and will shoot the responses over to my guy tomorrow (car is still there). He is waiting for a TPS as well.Will advise further as this goes on, hopefully for not that much longer. Link to comment Share on other sites More sharing options...
Colin Posted May 8, 2015 Report Share Posted May 8, 2015 My cone filter was clogged up and caused a similar issue. Fuel pressure would drop after a few minutes of driving. Link to comment Share on other sites More sharing options...
questtuner82 Posted May 8, 2015 Report Share Posted May 8, 2015 My ignition coil was bad and caused this. Ran good cold abd ran good when not in boost. As soon as i started building boost it fell on its face and felt like it ran out of fuel till i let off the throttle. Got very annoying trying to figure it out bc the symptoms seemed related to fuel but everything was new and or reconditioned Link to comment Share on other sites More sharing options...
yamahlr Posted May 8, 2015 Author Report Share Posted May 8, 2015 Once again, thank you one and all and will post when the issue is corrected. Meeting w/tech. today printed out posts and he is going to check some of the items indicated. Some he has already done to no avail. Ordered a downpipe today, will install when it arrives. Link to comment Share on other sites More sharing options...
yamahlr Posted May 8, 2015 Author Report Share Posted May 8, 2015 If it needs a mass air sensor, what are my options to get one? Although listed as available in the Mitsubishi parts catalog,dealer indicates it is discontinued. Any sources aftermarket or used? Thanks again guys! Link to comment Share on other sites More sharing options...
89StarQuestNYC Posted May 8, 2015 Report Share Posted May 8, 2015 You could upgrade to 1G DSM Turbo Mass. Link to comment Share on other sites More sharing options...
JohnnyWadd Posted May 9, 2015 Report Share Posted May 9, 2015 (edited) If it needs a mass air sensor, what are my options to get one? Although listed as available in the Mitsubishi parts catalog,dealer indicates it is discontinued. Any sources aftermarket or used? Thanks again guys! Used one from someone on here or a 1GMAS You could upgrade to 1G DSM Turbo Mass. X2 Edited May 9, 2015 by JohnnyWadd Link to comment Share on other sites More sharing options...
yamahlr Posted May 14, 2015 Author Report Share Posted May 14, 2015 Tech. working on it today, new Bosch coil +TPS unit, waiting for Top End down pipe, b pipe and HKS exhaust to arrive to arrive. Link to comment Share on other sites More sharing options...
88starchris Posted May 31, 2015 Report Share Posted May 31, 2015 I have this exact same problem! I'd love to know what works for you. Link to comment Share on other sites More sharing options...
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