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vwnewton, ASE Master and L1, Gm,VW,European
Category: Volvo
Satisfied Customers: 660
Experience:  Numerous years in European auto repair. You name it, I can help!
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1984 volvo 240: idles, but untill fully warmed up..throttle..clutch

Customer Question

have a 1984 volvo 240 gas, starts fine,and idles, but untill fully warmed up doesn't run well, seems lean ? if you roll on throttle it starts pop back through intake, you can drop the clutch and get it to tack up. once car is up to normal temp it runs good, restarts normal, and is good on power . some new parts, throtle position switch, water temp sensor, injector seals, plug wires, plugs dist cap, rotor. car is in good condition 207,000 miles well mantained. car is in good tune, have replaced vacume lines as needed etc. allso replaced mass air flow sensor from good running car no deference. have checked fuel presure, it's good has new fuel pump.       Thank Lynn
Submitted: 6 years ago.
Category: Volvo
Expert:  vwnewton replied 6 years ago.

Hello, Jason here to help. Did you replace the vacuum lines one at a time? What is the compression? What about the timing belt? Timing marks? Let me know, Jason

Customer: replied 6 years ago.
hello, jason sorry i didn't get back sooner, Yes all vacum lines are correct , and new or checked for leaks, Timeing belt is in good condition, timed on marks, and adjusted. compression is good 175 - 180lb's all four cyl. This car runs great after warm up. good power, idle etc. and will start without touching throttle. If i lett car sit and warm up to running temp. 185 200 deg. it will run out fine. If you try to drive it cold it will go flat if you give it gas, or axcellerate some then go flat on more demand, You can drop the clutch and tach it up, and this will clear it some. but still has trouble untill warmed up all the way. I have owned car for seven years and has allways performed well. it is very well mantained. Thanks Lynn
Expert:  vwnewton replied 6 years ago.
Do you have a vacuum guage to hook to the intake manifold. These cars have bad intake gaskets occasionally. I find them when running by a small stream of water over where the intake meets the head. A vacuum reading of less than 17 inches is not good at idle, or if the needle on the guage bounces then the valves could be a issue, with the backfiring. The intake if leaking will also cause backfires. Jason
Customer: replied 6 years ago.
hey jason, intake manifold gasket is good checked with straight oxygen with small tip all around intake runner were it meets the head. and sprayed carb cleaner around area know change in idle. It will only back fire when you try to give it alot of throttle when cold, more like a lean pop than a back fire. This is not a constant problem. I don't have a vacuum gauge to check idle vacuum. motor has good coprestion and runs, and idles fine when warmed up, I felt that rulled out bad valves or seats etc. ? Thanks Lynn
Expert:  vwnewton replied 6 years ago.
I was thinking of a sticking valve... Well, a injector cleaning might be in order, as it does sound like a lean backfire. Try supplying fuel into intake and rev it while doing that. If fuel starvation is the issue the car will rev well. Then that only leaves us with injections signal from ecu or plugging injectors. Let me know, Jason

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