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Followup To
Question - My postal address is Juris Kalnins, 2 Skaistkalnes str., Riga, Latvia, LV-1004, my e mail is jurkalnins@inbox.lv (it will be cheaper to scan and e-mail) Thank you for your help and kindness.
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Question -gauge is calibrated in KPa and the reading was -65KPa and converted in Psi it was 9.45...
About EGR- there is sort of leak on that black part with sensor or something- when i attach vacum to it sucks air from somewhere (on port named vac - where small pipe from intake manifold is attached), BUT I went to shop and asked for new one and it wasnt air tight on that port either so i did not buy it- so if i remove it from car it consists of two parts- metal attached to manifold and black plastic with vacum hose and wires- they are connected with two rubber hoses and that gives us two holes- vac and to manifold/ pipe from exhaust- where it sould be air tight?
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Followup To
Question - so I tested compression- it is about 130-135 psi in all cyls and tested vacuum and it is 9.5 psi at idle and is more or less steady. with vacum manometer and vacum pump I tested all vacum gauges going from manifold and could not find any vacum leakage. I did not check temp and other sensors, because do not know their location.there are no leak in exhaust system either. About egr- mechanic tried to close gauge from exhaust to intake manifolds, but it did not help. How to check egr valve, what to look for?
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Question -Thank you- very useful information. One more question- how to check intake manifold vacuum (if possible step by step) is it possible to do by myself? (do not trust much mechanics who are not my friends and i am tired waiting for visits to them- this wasnt first i visited)Do I need to check all those sensors if mechanic did car check with dignostic computer and did not see any problems with sensors (he connected to diagnostic socket of the car)?
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My Chrysler Grand voyager '94 3.3l is not working very welll and as there were no fault codes I went to mechanic and after check with diagnostic tool he stated that computer is adding adaptive factor as high as up to 50% and that means lean mixture. But the problem is that he could not find cause of it. Any ideas?
Answer -
Hi Juris,
That sort of adaptive factor excess unfortunately could be caused by many things:
ignition coil, the engine controller itself, the engine being worn out of spec, exhaust pipe/manifold leak, fuel pump pressure low, fuel filter, inlet filter to pump clogging up, spark wires, injector stuck closed, MAP sensor inaccurate, upstream O2 sensor inaccurate, fuel pressure regulator not maintaining pressure at proper level, spark plugs, wiring harness/connectors.
So look over the possibilities and see which might be the most likely is about all I can suggest. Talk to the mechanic to see which of them he verified. Of course, start with those things that are inexpensive you can do yourself.
Let me know if you find something suspicious or what it turns out to be.
Roland
I am using LPG on my car so when I try to accelerate or going up the hill it explodes in intake colector.(actualy it may happen in two cases- lean micture (gas analyzer shows it is normal, but was made even rich, but nothing changed) and if trere are fault in ignition system-plugs, wires etc.(they are checked and changed and nothing changes) If i drive using gasoline under the same conditions car twitches as some spark plugs are not working. mostly it happens out of city with speeds starting from 70 km/h. in city cycle mainly there are no problems (50 km/h). I already have changed spark plugs (4sets), ignition wires (2 sets)- they were tested on test machine and seems to be OK. I tried to change ignition coils to another used coil block, but there were no changes. I have checked everything about vacum leakage from intake collector (found some and fixed) and mechanic did the same but did not find any. O2 sensor, MAPsensor and others whatever they are seem to work properly (at least mechanic said that after using test computer and checking them) I must say that mechanic was recomended to me as one of best mechanics (autoelectrics) in the city and he have worked at toyota center (dealer center) and american car serice center so I think I can trust him.
Answer -
Hi Juris,
With the history of back firing I would certainly want to check out engine mechanical fundamentals such as:
Compression (100 psi minimum, no more than 25% variation between cylinders), fuel pressure (46 psi with vacuum hose attached, 48 psi with vacuum removed), check the egr (exhaust gas recirculation) valve to make sure that it is not leaking (remove and inspect passageway); measure the resistance of the coolant temp sensor when the engine is warm (900-600 ohms at 170-200F) and the intake air temp sensor (170-20 ohms at 180-200F). I would also check the intake manifold vacuum to be sure that it is steady and at least 13 psi. I wish I could be of more help, Juris, but at a distance it is very challenging to do that.
Roland
Answer -
Hi Juris,
To check the vacuum all you have to do is attach a vacuum gauge to any of the several ports on the intake manifold that now have vacuum hoses attched to them, using a T-fitting so that you don't disturb the vacuum supply to whatever is already on that port. The reading should be steady at a reading between 13 to 22" while idling. On the sensor checks, whether the mechanic noticed that one of the sensors was outside the normal range depends upon his experience level. The degree of outside-the-spec reading of any sensor is fairly severe for a code to be set by the engine controller, so it is possible to have a problem without having any codes set. For example I had a 2.5L 4-cyl '89 engine refuse to idle or run well, but without setting a code. The Chrysler dealer tune-up mechanic noticed that the MAP sensor was viewing the ambient pressure at a much different value than was true, but still no code was set because the value was still within the range of the possible. So you might ask the mechanic to look again at all the readings of sensors to see it they are consistent with other known facts about the engine and the environment.
Roland
Answer -
Hi Juris,
That reading of 9.5 psi at idle is too low. (Are you sure that the gauge was calibrated in psi rather than a metric system unit)? Could the power brake vacuum hose be loose; are the power brakes working well (unit itself not leaking vacuum)? On the egr, you would simply disconnect it from the pipes to which it is attached (intake manifold/pipe coming from the exhaust manifold) and blow or suck on either of the fittings to see if you can draw air thru it. It should be airtight. There has to be a leak of some sort or the vacuum gauge would be at least 13 psi. Also check th
e smaller vacuum line(s) that branch off of the power brake vacuum hose line to be sure they aren't leaking.
Roland
Answer -
Hi Juris,
Sorry to be slower in response than usual, I was out of town yesterday. I would propose that I copy and airmail you a couple of pages on how to test the entire egr system taken from the Haynes manual which covers engine that you have. It is too lengthy for me type in all the tests, and also there are some useful diagrams that give the proper names to the parts. So if you will tell me a postal address I'll copy the pages and mail them to you promptly, at no cost.
Roland
AnswerHi Juris,
I'll copy and mail it today. It will be more readable when you get it, I believe. There shouldn't be any air leaks in normal vacuum connection situation, so it may be that you have a bad solenoid, bad valve, or incomplete set of hose connections. So this info will help you sort it out.
Roland
