Hi all, I'm looking for some help tracking down a very intermittent hesitation that only happens above 80 degrees F and above 3500 RPM. My Spyder is a 2004 and very well loved with 226,000 on the clock. I've had it for the last 13 years and it's a daily driver. I replaced the engine last summer with a JDM I got off ebay. I've put about 10,000 miles on it since the engine replacement. It has been running great, idles smooth and uses no oil. It just started doing this as our weather warmed up. The hesitation is brief with just a couple stutters and then right back to normal. I drove it 100 miles last weekend. It hesitated a couple times on the freeway and then never did it again the rest of the trip. It does not set a code. I put new plugs in with the new engine and cleaned the throttle body. I did reuse the original injectors. Could this be dirty injectors? I just cleaned the MAF and replaced the air filter and it still does it. Does anyone have any ideas?
Topic starter
Posted : June 26, 2020 4:40 pm
Maybe one or both of the upstream O2 sensor(s).
How do the LTFT look for both banks?
A quick test is to do a hard ECU reset, pull the battery negative cable off for 10-20 minutes and then reconnect, to reset the base fueling maps and see if it clears up initially.
Mono Craft GT-300 with a few upgrades...
Posted : June 27, 2020 7:21 am
Is the car using the original MAF sensor?
Posted : June 27, 2020 8:16 am
The MAF and 02 sensors are original.
Topic starter
Posted : June 27, 2020 10:31 am
With the milage you have Im surprised that the 02 sensors lasted this long. 02 sensors are usually replaced when the heater wire is severed but they should actually replaced at 80k miles as they drift. The MAF sensors also drift with age and milage. Usually as these electronic sensors get older they can be effected by varying temps that can throw off their readings which can effect fueling.
I would first replace both the MAF and 02 sensors since they need to be replaced. I would also check your fuel trims if you have access to an ODB2 reader to pin point the issue. It might or might not solve the issue just by replacing these parts however these items should be dealt with as age related items that need replacement and so you can get accurate readings if the problem persists to locate the issue.
Posted : June 27, 2020 11:13 am
marsrock7 reacted
Thanks much. I’ll start looking for MAF and 02 sensors.
Topic starter
Posted : June 27, 2020 1:10 pm
Circling back with the fix on this - MAF and 02 sensors were replaced with no change. I also replaced the plugs and inspected the coil packs but it still hesitated occasionally. Then I saw a post that pointed me to the crank sensor. I can't find it now but it basically said if you've got weird issues try replacing the crank sensor - pretty sure it was Dev on the old site. When I swapped the engine I did not swap the crank sensor. I pulled my crank sensor off the old engine and swapped it in - no more intermittent hesitation.
Topic starter
Posted : November 3, 2020 1:41 pm
Uncle Mush reacted
That's great! Congratulations on getting that all sorted out.
Posted : November 3, 2020 1:48 pm
thanks for closing the loop on this with an actual diagnosis. Happy motoring!
Though not a long term solution - when I had a crank sensor issue (No Start due to polarity issue with the JDM swap part), i could disconnect the CPS and engine ran, though I found out from this site - it was running in a fail safe mode that was rough on plugs and coils (firing all the time). It was good to help me diagnose the CPS though.
Glad you got it sorted
Posted : November 9, 2020 10:39 am
Fail safe mode in this situation and the cam sensor is interesting because the car can keep going for thousands of miles although it will deteriorate the spark plugs. I do think its probably not good on the engine and that is why people shouldn't assume the CEL is no big deal.
Posted : November 9, 2020 10:52 am