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I need help diagnosing an engine miss, rough idle....
Ok I just test drove an 89 Renix, 2 WD, 112,000 original miles, that I am planning to buy tomorrow. It's a jewel! But the owner says the local shell gas station's greek mechanic checked it out and says the #5 cylinder is shot. I think blown was the word he used, but this is second hand, so who knows.
I test drove it, and I took it to WOT for a few seconds, from 5 mph to say 20 mph, with no problem!!!!!
At ilde, or cruising, It acts like its running on 4 or 5 cylinders. The Exhaust system Cat converter and muffler and exhaust pipe are already new.
The CCV system is working perfectly, air filter is new, I checked the rotor and cap, they were OK, the spark plugs are new, and were changed just 9,000 miles ago and again 10 miles ago.
The worst spark plug had a thick (1/8") light brown deposit on the electrode after 9,000 miles. The second worst looked OK to me, not great, but a thin layer of light brown deposit, not bad like the worst one. Unfortunately the owner did not mark or track the cylinder the plugs came out of. No oil on the plugs at all.
TPS responds OK from idle to WOT in first gear. I did not take it over 25 mph, and only drove it one block. Tranny feels solid. THis Jeep looks like it was parked in an air conditioned garage for 18 years, and barely driven. But I did see some signs of some sludge under the valve cover area. Oh, and it has no overheating problems, it still has the closed Renix cooling system with about 1-2 year old standard Renix poly bottle with cap, and the AC was working while I ran tests on the engine for about 15 minutes. I tried some obvious simple stuff like cleaning the battery cables while I was checking it out. I found a disconnected EGR vacuum line to the EGR solenoid, and reconnected it, but had no effect. The EGR looked new.
O2 sensor is reportedly the orignal. It just passed the fairly strict Houston, Tx emissions tests but only after getting the new muffler and new cat, and just before the rough idle, engine miss started up.
I am thinking it might be a leaking injector flooding #5. OH, I forgot to mention I could smell raw fuel out the exhaust the first few minutes he ran it. The miss settles down at high rpms, it is still there, but much less noticable at 3,000 rpm, and quite noticable at idle. None of the injectors are leaking externally at all! But, the body color was black on three injectors, and silver on the other three, telling me some of the injectors have been swapped out by the original owner at some point.
He is having dash gauge problems, in particular he said the digital clock has been rapidly fadding from brite to normal (night to day view) , since his engine problem started. I also noticed the Voltmeter was reading fairly low, like in the 8 to 10 volt range, but I did not have time to investigate that further. I should have thrown my volt meter on it, but the owner was short on time and running late for an apt. I also forgot to check the oil dipstick, but he said he had just changed the oil and filter.
Ideas???????
Ok I just test drove an 89 Renix, 2 WD, 112,000 original miles, that I am planning to buy tomorrow. It's a jewel! But the owner says the local shell gas station's greek mechanic checked it out and says the #5 cylinder is shot. I think blown was the word he used, but this is second hand, so who knows.
I test drove it, and I took it to WOT for a few seconds, from 5 mph to say 20 mph, with no problem!!!!!
At ilde, or cruising, It acts like its running on 4 or 5 cylinders. The Exhaust system Cat converter and muffler and exhaust pipe are already new.
The CCV system is working perfectly, air filter is new, I checked the rotor and cap, they were OK, the spark plugs are new, and were changed just 9,000 miles ago and again 10 miles ago.
The worst spark plug had a thick (1/8") light brown deposit on the electrode after 9,000 miles. The second worst looked OK to me, not great, but a thin layer of light brown deposit, not bad like the worst one. Unfortunately the owner did not mark or track the cylinder the plugs came out of. No oil on the plugs at all.
TPS responds OK from idle to WOT in first gear. I did not take it over 25 mph, and only drove it one block. Tranny feels solid. THis Jeep looks like it was parked in an air conditioned garage for 18 years, and barely driven. But I did see some signs of some sludge under the valve cover area. Oh, and it has no overheating problems, it still has the closed Renix cooling system with about 1-2 year old standard Renix poly bottle with cap, and the AC was working while I ran tests on the engine for about 15 minutes. I tried some obvious simple stuff like cleaning the battery cables while I was checking it out. I found a disconnected EGR vacuum line to the EGR solenoid, and reconnected it, but had no effect. The EGR looked new.
O2 sensor is reportedly the orignal. It just passed the fairly strict Houston, Tx emissions tests but only after getting the new muffler and new cat, and just before the rough idle, engine miss started up.
I am thinking it might be a leaking injector flooding #5. OH, I forgot to mention I could smell raw fuel out the exhaust the first few minutes he ran it. The miss settles down at high rpms, it is still there, but much less noticable at 3,000 rpm, and quite noticable at idle. None of the injectors are leaking externally at all! But, the body color was black on three injectors, and silver on the other three, telling me some of the injectors have been swapped out by the original owner at some point.
He is having dash gauge problems, in particular he said the digital clock has been rapidly fadding from brite to normal (night to day view) , since his engine problem started. I also noticed the Voltmeter was reading fairly low, like in the 8 to 10 volt range, but I did not have time to investigate that further. I should have thrown my volt meter on it, but the owner was short on time and running late for an apt. I also forgot to check the oil dipstick, but he said he had just changed the oil and filter.
Ideas???????